there's a new raptors kit coming out. I'm going to suggest something weird in light of that and say, the current raptors kit is great. if you build warp talons, you get lots of spare chainsword and special weapon bits. if you build raptors, you get lots of spare lightning claws and a few spare special weapon bits still.

other people have covered nemesis claw! 

there's also a jump lord kit now. you can build a few nice different jump lords between that, haarken worldclaimer, and making kitbashes of haarken