The first thing I'd point out is you can't have the Dark Lance AND the Splinter Cannon in the same 10 man squad... so just remember that when putting together your new warriors!
The second is which HQ to use is, well, a big question and just because you'll have a lot of Warriors on Raiders doesn't answer it one way or the other. In my opinion, take the Haemonculus if
You want to take some Wracks as troops
You just want a cheap HQ to buy more guns
And take the Archon if
You want an HQ who provides a bit of combat punch
You want an HQ that's about as survivable as we can do
Hope this helps.