I have used every bot mentioned here except the php bot.
If your definition of "best" means "most powerful" and "highest potential for profits" then Haasbot wins easily.

Haasbot Pros/Cons:
+ Supports the most number of exchanges. Even more than C.A.T. Bot.
+ Supports more than 12 trading strategies. The only bot I know that supports ichimoku cloud strategy.
+ Highly customizable. Multiple strategies and safeties can be used together. Also has custom scripting interface.
- Does not run in the cloud. Can be difficult to install. Their support person is not a technical person and can't help much with technical issues.
- Not for beginners. The pre-configured strategies were not profitable. Best for experienced traders who already have a winning strategy and just need a way to automate their strategy.
- Pricey.