Best boot for xc in my opinion is the Nunn Finer American Style. Fantastic stuff. But, at the lower levels you don't really need that much boot. Never hurts though.
Find the lining that works best for your horse. Fleece/sheepskin is normally avoided on xc because it soaks up the water, but some horses need boots lined with this because they're allergic to neoprene or other liner materials.