Without more information, a meaningful answer isn't really possible. Singles or doubles make a big difference, as does your height/weight and even what your buddies are wearing.
In general, the manufacturer isn't all that important when choosing a backplate. Single tank divers normally choose steel plates for their weight. Doubles divers might choose aluminum for the same reason. Traveling divers might choose aluminum or even high-impact plastic. Tall divers sometimes choose one of the longer plates. I like mine to have lotsa holes in them to hang argon bottles and SMB's from. I don't like plates that have slots instead of holes for the tank bolts.
Make sure that the wing will fit with your tank. Halcyon made (IMHO) a mistake a couple of years ago when they came out with a single tank wing design with an internal STA that wouldn't fit well on some backplates made by other manufacturers. Be sure to assemble whatever system you're considering before you buy so that you can see that it fits together properly. Value design flexibility over creative novelty.
Search BWOD and you'll get some information about wing design that is pertinent.
Frankly, I'd steer away from Halcyon right now. They've been having a string of QC issues with a couple of their inflator designs over the past few years and are in the middle of a big recall campaign. After paying out of my own pocket to replace my old cludgy inflators with new improved ones, the new ones have now been recalled to be replaced with newer ones...they charge a premium price for a less-than-advertised level of quality.
In addition to the wings made by Dive Rite, Halcyon and OMS, I'd definitely look at the wings being sold by OxyCheq and Deep Outdoors. I've not had a chance to play with the OxyCheq wing but I have a lot of confidence in Patrick Duffy. The Deep Outdoors wings include a line of the dreaded BWOD (read "internal compression bands") but some don't. The ones I've seen are well made and people have been saying nice things about them.
For what it's worth, I own two Halcyon wings and one from ScubaPro. I've got backplates from FredT, Halcyon and Dive Rite and a soft pack from ScubaPro.
Happy hunting!