An aluminum back plate and standard or deluxe pivot ring harness tends to be very compact, lightweight and travel freindly. I also like the way it distributes the weight during the dive.
A back plate is also very modular in that you can add (or remove) weight pouches, pockets, D-rings, etc as the situation dictates and you can use accessories form just about any manufacturer. Personally, I think OMS pockets and pouches are a little bulky for my tastes and their customer service absolutley sucks. In fact I have never gotten a response from them. Ever.
If you go the BP route, a one piece standard harness is considered more kosher with the hog and hard core DIR divers, but a pivot ring harness is much more readily adjustable as the chest strap can take up the slack that results if moving from a dry suit to a tropical shorty or t-shirt with no need to adjust the webbing itself. The quick release is also nice and despite the nay sayers who scream "failure point", it's virtually impossible to break one and if you did, the other strap and waist belt will still keep the BP/wing in place.
The comfort harness is ok, but I don't like the way it attaches to the plate and you can gain 90% of the comfort with a pivot ring harness and 1/4" neoprene pads around the shoulder straps. OMS and dive rite both sell them for $25-$30, but I sew my own out of old wet suits and sew on velcro from wal-mart.