Choosing an LLM in 2026: The Practical Comparison Table (Specs, Cost, Latency, Compatibility)

The uncomfortable truth: “model choice” is half your prompt engineering

If your prompt is a recipe, the model is your kitchen.

A great recipe doesn’t help if:

  • the oven is tiny (context window),
  • the ingredients are expensive (token price),
  • the chef is slow (latency),
  • or your tools don’t fit (function calling / JSON / SDK / ecosystem).

So here’s a practical comparison you can actually use.

Note on “parameters”: for many frontier models, parameter counts are not publicly disclosed. In practice, context window + pricing + tool features predict “fit” better than guessing parameter scale.


1) Quick comparison: what you should care about first

1.1 The “four knobs” that matter

  1. Context: can you fit the job in one request?
  2. Cost: can you afford volume?
  3. Latency: does your UX tolerate the wait?
  4. Compatibility: will your stack integrate cleanly?

Everything else is second order.


2) Model spec table (context + positioning)

This table focuses on what’s stable: family, positioning, and context expectations.

| Provider | Model family (examples) | Typical positioning | Notes | |—|—|—| | OpenAI | GPT family (e.g., gpt-4o, gpt-4.1, gpt-5*) | General-purpose, strong tooling ecosystem | Pricing + cached input are clearly published. | OpenAI | “o” reasoning family (e.g., o3, o1) | Deep reasoning / harder planning | Often higher cost; use selectively. | Anthropic | Claude family (e.g., Haiku / Sonnet tiers) | Strong writing + safety posture; clean docs | Pricing table includes multiple rate dimensions. | Google | Gemini family (Flash / Pro tiers) | Multimodal + Google ecosystem + caching/grounding options | Pricing page explicitly covers caching + grounding. | DeepSeek | DeepSeek chat + reasoning models | Aggressive price/perf, popular for scale | Official pricing docs available. | Open source | Llama / Qwen / Mistral etc. | Self-host for privacy/control | Context depends on model; Llama 3.1 supports 128K.


3) Pricing table (the part your CFO actually reads)

Below are public list prices from official docs (USD per 1M tokens). Use this as a baseline, then apply: caching, batch discounts, and your real output length.

3.1 OpenAI (selected highlights)

OpenAI publishes input, cached input, and output prices per 1M tokens.

| Model | Input / 1M | Cached input / 1M | Output / 1M | When to use |
|—-|—-|—-|—-|—-|
| gpt-4.1 | $2.00 | $0.50 | $8.00 | High-quality general reasoning with sane cost  |
| gpt-4o | $2.50 | $1.25 | $10.00 | Multimodal-ish “workhorse” if you need it |
| gpt-4o-mini | $0.15 | $0.075 | $0.60 | High-throughput chat, extraction, tagging |
| o3 | $2.00 | $0.50 | $8.00 | Reasoning-heavy tasks without the top-end pricing  |
| o1 | $15.00 | $7.50 | $60.00 | “Use sparingly”: hard reasoning where mistakes are expensive |

If you’re building a product: you’ll often run 80–95% of calls on a cheaper model (mini/fast tier), and escalate only the hard cases.

3.2 Anthropic (Claude)

Anthropic publishes a model pricing table in Claude docs.

| Model | Input / MTok | Output / MTok | Notes |
|—-|—-|—-|—-|
| Claude Haiku 4.5 | $1.00 | $5.00 | Fast, budget-friendly tier  |
| Claude Haiku 3.5 | $0.80 | $4.00 | Even cheaper tier option  |
| Claude Sonnet 3.7 (deprecated) | $3.75 | $15.00 | Listed as deprecated on pricing  |
| Claude Opus 3 (deprecated) | $18.75 | $75.00 | Premium, but marked deprecated  |

Important: model availability changes. Treat the pricing table as the authoritative “what exists right now.”

3.3 Google Gemini (Developer API)

Gemini pricing varies by tier and includes context caching + grounding pricing.

| Tier (example rows from pricing page) | Input / 1M (text/image/video) | Output / 1M | Notable extras |
|—-|—-|—-|—-|
| Gemini tier (row example) | $0.30 | $2.50 | Context caching + grounding options  |
| Gemini Flash-style row example | $0.10 | $0.40 | Very low output cost; good for high volume  |

Gemini’s pricing page also lists:

  • context caching prices, and
  • grounding with Google Search pricing/limits.

3.4 DeepSeek (API)

DeepSeek publishes pricing in its API docs and on its pricing page.

| Model family (per DeepSeek pricing pages) | What to expect |
|—-|—-|
| DeepSeek-V3 / “chat” tier | Very low per-token pricing compared to many frontier models |
| DeepSeek-R1 reasoning tier | Higher than chat tier, still aggressively priced |


4) Latency: don’t use fake “average seconds” tables

Most blog latency tables are either:

  • measured on one day, one region, one payload, then recycled forever, or
  • pure fiction.

Instead, use two metrics you can actually observe:

  1. TTFT (time to first token) — how fast streaming starts
  2. Tokens/sec — how fast output arrives once it starts

4.1 Practical latency expectations (directional)

  • “Mini/Flash” tiers usually win TTFT and throughput for chat-style workloads.
  • “Reasoning” tiers typically have slower TTFT and may output more tokens (more thinking), so perceived latency increases.
  • Long context inputs increase latency everywhere.

4.2 How to benchmark for your own product (a 15-minute method)

Create a small benchmark script that sends:

  • the same prompt (e.g., 400–800 tokens),
  • fixed max output (e.g., 300 tokens),
  • in your target region,
  • for 30–50 runs.

Record:

  • p50 / p95 TTFT,
  • p50 / p95 total time,
  • tokens/sec.

Then make the decision with data, not vibes.


5) Compatibility: why “tooling fit” beats raw model quality

A model that’s 5% “smarter” but breaks your stack is a net loss.

5.1 Prompt + API surface compatibility (what breaks when you switch models)

| Feature | OpenAI | Claude | Gemini | Open-source (self-host) | |—|—|—|—| | Strong “system instruction” control | Yes (explicit system role) | Yes (instructions patterns supported) | Yes | Depends on serving stack | | Tool / function calling | Widely used in ecosystem | Supported via tools patterns (provider-specific) | Supports tools + grounding options | Often “prompt it to emit JSON”, no native tools | | Structured output reliability | Strong with constraints | Strong, especially on long text | Strong with explicit schemas | Varies a lot; needs examples + validators | | Caching / batch primitives | Cached input pricing published | Provider features vary | Context caching explicitly priced | You implement caching yourself |

5.2 Ecosystem fit (a.k.a. “what do you already use?”)

  • If you live in Google Workspace / Vertex-style workflows, Gemini integration + grounding options can be a natural fit.
  • If you rely on a broad third-party automation ecosystem, OpenAI + Claude both have mature SDK + tooling coverage (LangChain etc.).
  • If you need data residency / on-prem, open-source models (Llama/Qwen) let you keep data inside your boundary, but you pay in MLOps.

6) The decision checklist: pick models like an engineer

Step 1 — classify the task

  • High volume / low stakes: tagging, rewrite, FAQ, extraction
  • Medium stakes: customer support replies, internal reporting
  • High stakes: legal, finance, security, medical-like domains (be careful)

Step 2 — decide your stack (the “2–3 model rule”)

A common setup:

  1. Fast cheap tier for most requests
  2. Strong tier for hard prompts, long context, tricky reasoning
  3. Optional: realtime or deep reasoning tier for specific UX/features

Step 3 — cost control strategy (before you ship)

  • enforce output length limits
  • cache repeated system/context
  • batch homogeneous jobs
  • add escalation rules (don’t send everything to your most expensive model)

7) A practical comparison table you can paste into a PRD

Here’s a short “copy/paste” table for stakeholders.

| Scenario | Priority | Default pick | Escalate to | Why |
|—-|—-|—-|—-|—-|
| Customer support chatbot | Latency + cost | gpt-4o-mini (or Gemini Flash-tier)  | gpt-4.1 / Claude higher tier | Cheap 80–90%, escalate only ambiguous cases |
| Long document synthesis | Context + format stability | Claude tier with strong long-form behaviour | gpt-4.1 | Long prompts + structured output |
| Coding helper in IDE | Tooling + correctness | gpt-4.1 or equivalent | o3 / o1 | Deep reasoning for tricky bugs |
| Privacy-sensitive internal assistant | Data boundary | Self-host Llama/Qwen  | Cloud model for non-sensitive output | Keep raw data in-house |


Final take

“Best model” is not a thing.

There’s only best model for this prompt, this latency budget, this cost envelope, and this ecosystem.

If you ship with:

  • a measured benchmark,
  • a 2–3 model stack,
  • strict output constraints,
  • and caching/batching,

…you’ll outperform teams who chase the newest model every month.

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