Thanks so much for the edit and critique Flappy, I really appreciate it and your edit gives me some new ideas that im going to try. I just want to say that im trying to keep the size under or about 32x32.
Palette:
Perfectly reasonable; will try to bump up the gray/white's contrast. Im just worried about making them too dark as im still inexperienced with palettes. Will also remove yellow on white, thanks for the input!
Design:
Regarding blue's orange armour; my intent was that it was supposed to be bronze, mimicking ancient greek armour but i understand that it could lead to misreading and confusion. I'll try to find an alternative to this.
Regarding the leg skin; this is really valuable input; i wasn't aware it created noise so i will take steps to remedying that, thanks!
Regarding your last comment; thanks for pointing this out, will work to ensure certain design choices are unique to each colour/faction.
Your comments have been really helpful and they've given me a lot to think about; thanks so much! Hopefully i can repay you one day for your advice. I've found when you're making something (regardless of the medium) you can get bogged down with what you're doing and you become unable to view your work with an independent, unbiased eye, so differing views are always welcome.
r1k: Thanks for the comment; will edit it and generally play around with it and see what it looks like if i make them less bent/sticking out less.
So i've been spending the last few days re-doing some of the classes/characters. Haven't gotten onto the medieval (purple) ones yet and i still haven't finished any of the other ones but here's what i've got:

For comparison's sake old version is on left, new on right, although not all have previous versions.
I was disappointed with most of them last time, but im hoping they look less stock and have character/flavour to them, rather than just looking like generic military units.
Got to say again i really appreciated your input flappy; i incorporated most of your edit's details in my new attempts. Tried adding a roman-flavour to one of the blue units, added some celtic (mainly scottish) elements to the green as well.
Sorry for the double post; i just want to know whether this is a step in the right direction in regards to making them look better and "different".
Further update (Some more done):
