Wave = BADA, 1 GHz processor, Awesome Screen, Interface is a bit cluttered. It is very fast but most pricey. Lesser Applications are there and even lesser free apps from Samsung store.
Wildfire = ANDROID 2.1 upgrade to 2.2 in pipeline, a slower processor (528 MHz) than Wave but great user experience. It is a complete value for money. Lots of free apps from android market. Camera is 5MP and that too with LED flash.
Galaxy 3 = ANDROID 2.1 but slowest among all 3(528 MHz but lesser RAM). It is least priced. Camera resolution also is lower than wildfire I guess.
My opinion, go for wildfire, I am using one myself.