Gears 1: Lancer
Gears 2: Hammerburst
Gears 3: Retro Lancer

The End.

Mind you the smurfing Lancer is a nasty god damn weapon in 3 as well, and is only just marginally inferior to the Retro Lancer in online play due to people's play styles. If people hung back a bit and didn't make it their primary objective to run up to you and shoot you with the Gnasher, the Lancer might just prove to be superior. The Hammerburst is depressingly poor in 3 though. The clip size is pathetic.