For the warrior, I like the leather around the waist, and I love that you're actually adding the strapping.
The size of the spaulder/top lame of the pauldron looks a bit WoW-y to me. Blizzard does love a good spaulder. Given the note about the bone, I imagine you're making the top lame big enough to cover the lack of an actual spaulder. May be a good compromise!
The knee of the armor isn't jointed. Between the length of the upper leg armor and the boot, I'm concerned that it only looks right because the model's leg is straight. When he bends that knee, the top of the boot will stand up, and the joint will be completely exposed...you'll probably cover it in mail, but that's backwards - armor evolved to cover the joints first, slowly adding sheets of mail outward, and leaving mail underneath. Elbows have a bit of the same. I imagine it's something to do with animating the characters that has driven fantasy armor design this way, but it always kind of jumps out at me - don't know if it's something you'd care to address.
The upper leg armor is visually tied to the bracer via the 'border' that each has. Perhaps continue that tie-in to the solid center ridge?
Alternately, I think it's the bracer that's throwing me off a bit - everything else is overlapped and strappy, but the bracer is sleek and whole-formed.
Your helm is somewhere between a salet and a barbute. The T-faced barbute's always a favorite because it leaves the character's face visible, but IMO your design is crying out for a salet and bevor. If you don't go with a bevor, consider bringing the neckline of the chest piece up. Like Hhean said, though, it really depends on what they're going to be used for.
And, of course, take all of this only as requested criticism given by someone without a lick of artistic talent of his own!
I like the ranger. Good fantasy ranger. The collar on the mantle/capelet is a nice touch, and while I've seen that style of boot a lot, I think it works really well on this design.