Best combination of quality, customer service and price would be Dynotune! http://www.dynotunenitrous.com/store...?idproduct=115
But Magic hit the nail on the head you will get a lot of opinions and preferences.
There have been a lot of write ups lately on this subject - I would do a search you will see a ton of info. NX and TNT both post on this board also - both carry excellent products.