Lots opinions....the hottest and most bang for the low priced buck is the new V&H FP3......around $300 shipped if you shop a little. The FV2 is also awesome and a little more capable of doing a cam change but V&H just opened the code up so much more capability than when 1st released and also has an "auto tune" or self learning mode.
Lots of threads on both here, do a quick search and you should be busy for a while.