there the only to hoppers ive used, and personaly i prefer the vlocity,
it feels nice on my marker, it weighs a little less and overall i prefer it. downside is it will eat batteries so will need to get an aftermarket board ive got two vlocities 1 with a gangster chip and 1 with a virtue chip both work awsome and have the custom modes to program the hopper. some people may say there loud only time i find this is when its empty. also there fairly easy to take apart.
Halo's good reliable hopper cheaper than the vlocity, and they dont really need a chip, only thing may want to get for it would be a 9v converter, don't eat batteries, quiet and sit fairl nice on your marker, (can't say weather easy or not to take apart asnever did with mine)
my prefernce would be a vlocity and a lot of pro teams use them aswell if you're into that sort of thing.
hope this helps.
will