i love my reloader b, its fast and no eyes to get smegged up. plus they have the feedneck roughly in the middle which can help with balance.
eggs are cheap tho, and with most tourneys capping at 15.4 bps are fast enough, but can be a bit fragile, things can be done however to eliminate this (pm if you own one), and they tend to be back heavy, which some ppl kinda like.
Halos are a reloader b with eyes instead of sound activation. keep they eyes clean and they are as fast as a reloader b, but i have tended to find that they are heavier on batteries than the reloader b.
finally the vlocity. haven't had me hands on one yet, so can't comment.
Don't be tempted by just what looks cool tho, u'll look better playing a great game than posing with sweet kit.