Depends on what your botting. At the moment with recent bans Powerbot is less favorable in certain skills due to many of the bans coming from people using Powerbot scripts (with this new 'bot watch'). People using scripts for Dung and LRC are being banned. SIMBA is favorable if your looking to bot in LRC. But for other skills using Powerbot is fine. It is still very reliable and still has the largest script selection.
Apparently the 4048 update which was recently pushed on powerbot created a mess and the majority of scripts aren't functioning properly. I would wait until this has been solved...