ScoobieDooo once bubbled...
Well,
There are several schools of thought on this one.
I'd go with their 35 or 45# wing. I like a single tank wing to be about 45#, but thats my opinion. Most guys that go with Halcyon's pick like a 27 or 36# wing. I like a bit more. Thats JUST IMO, thats not gospel nor fact.
45# is plenty even if you were to be carrying an AL40 around or a big PONY bottle, reels, perhaps camera's, maybe a scooter, etc.
I have the 100# bungee wing but only because I eventually want to go to twins. The bungee keeps the wing from 'flapping' around when used on a single tank, otherwise you'd get a 'taco affect' of the wing wrapping around your tank. That would be a lot of drag.
If your going into the DIR direction, you won't want a bungee wing. Thats a whole 'nother can of worms I won't open, but again, there are two schools of thought on that one. Choose your weapon accordingly.
If you have plenty of funds, go a wing for singles and one for twins later. OMS, Dive Rite, Halcyon and now Oxy Cheq all have good wings. I'd say the Halcyon and Oxy's are build a bit better (at least the bladder) than the OMS. I have no experience with Dive Rite's. Oxy Cheq's look like they will be good.
I'd probably look at the 35# for traveling or warm water diving and 45# for cold water diving with heavy gear.
OMS's 35 or 45's can be had for less than $200, I believe. The 100# is more.
Good luck.