A tyranid ripper with underground swarm option cuz then I can hide from enemyes and attack them from behind with my fellow ripper brothers and because usually rippers are used for collecting bio mass so I don' t get shot so often, and If I die probably mother hive mind will generate me again.
Or a Dark Eldar cuz of Metal, Leather, Spykes, Sex, Drugs and all that suff
In the end there is only Chaos...
Tyranids: Ragnarök Hivefleet Space Marines: Salamanders Chapter Dark Eldar: Blood Dragon Kabal
Chaos Daemons: Seed Of Destruction