I ride western and I use Ariat full grain leather chaps. Previously, I used suede chaps, but they attracted so much dirt and hay that it wasn't worth it. I love my leather ones--they don't attract dirt and they have zippers (and comfy elastic inserts), so the lead rope doesn't get stuck to my leg anymore. :)
Half chaps are way cheaper than buying a nice pair of field boots, so I would go with them. Also, if you are still growing, they aren't as expensive to replace once you have outgrown them.