[>BKA< T Wrecks]

This question has been asked several times already, but never answered clearly in favour of one bot. And that's for a reason:
What does "best" mean?
Is it the bot that's hardest to play against?
Is it the bot that doesn't need waypoints, thus supporting every map?
Is it the bot that is best at getting along with buttons, doors, lifts etc. ?
Is it the bot that's best to control by Dedicated Server commands?
Is it the bot that crashes least?
Is it the bot that has the most varied navigation?
Is it the bot that's least CPU-hungry?
Is it the bot that features best compatibility with other MM / AMX plugins?
Is it the bot that's easiest to set up, or the one that's best to fine-tune?

Loads of questions, and they all depend on your personal preferences, your hardware, your playing skills and habits, your preferred maps or map types, your preferred weapon modes (maybe you like knife arenas?), your server type, your plugin configuration and so on. There is no general answer. Even most of these individual questions I listed cannot be answered clearly, because answers would also depend on the particular circumstances.

Besides, I don't think that anybody has tried all CS bots available.

In order to find the best solution for you, maybe describe a bit what you expect from your bots, how you want to use them and which maps you play (most bots need waypoints, but for some, waypoint files are easier to find than for others.). Then maybe we can narrow down the choice a bit, but you will never read "bot x is clearly the best" in replies or posts of the serious people at these forums.