Any clothing you like (that's the answer). As to whether or not to describe them, I've never read a medieval fantasy novel where they ignored the clothing (for the most part). I consider clothing to be a part of setting in a sense. How does it help characterize? How does it say something about the character/story?
For example, in GRRM's ASOIAF series, he's always describing clothing, but it's efficient: a sentence tops. Sansa wore something pretty and the prose is pretty, too, when Martin describes it because she's still living in a fantasy world where she believes knights are all good and fair ladies receive royal favor and courtesy.
Look at the successful writers. How do they do it? This is one thing that you can look for when you are reading: e.g. "read like a writer." Food is another one that catches my attention.
As for style, well, that's up to you. They didn't just wear tunics and leggings in medieval times. Men wore simple trousers and shirts (belted or not). Women wore an array of dresses (or perhaps they dress less girly in your world and things are more gender-neutral). Also consider non-western gear. Middle Eastern garb, Asian, Mongol, etc.
Clothing may not be important to you, but it might be to your characters--at least in specific situations. I probably have some article of clothing mentioned in about half the chapters. It's never more than a sentence (or even half a sentence) and always exists to show something about the scene, situation, character, plot, or theme. "Rob hated his formal doublet with its large, slashed sleeves and collar that dug into his skin." Not much to that, but it shows that Rob doesn't like dressing up for whatever reason. He feels confined. He might feel like his garb is too showy (large, slashed sleeves). The reader can infer a lot.
