The Sherman Filterbank is an absolute monster. It's gritty, dirty, filthy, and whilst it's interface isn't particularly intuative if you put some sound into it and move some controls - you're guaranteed to hear something nice.
Conversely, some would consider this to be a deal-breaker as, simply put, you'll never hear the same thing twice from this beast.
In summary, it's pricy but very fun. Get yourself a Sherman.