I did some research about what LLM has the best deep search capability since I pay for 5 of them (GPT-5, Perplexity, Gemini 2.5 Pro, Grok 4, Claude Opus 4.1).

Horizontal: the LLM that valuated the answer. (GPT-3 is o3).
Vertical: the LLM that gave the anser.

Interesting is of course, to what question, and what are the answers? I will research several questions (5) and will evaluate them all and will share it as a site later.

Perplexity should be the best regarding this. But after some usage I started doubting. If you would care about speed - yeah, could be.

Soon I'll have a in depth results for you so it'll easier to pick one if you don't want to end up as i do with 5 of them.