I like nylon on gloves and cordovan tabs.
In addition to plain cowhide gloves, I've used a Superglove (cordovan tips), a Duraglove (nylon tips, and now a big shot (nylon tips with inserts). I like the Big Shot the best so far with the Duraglove second.
I don't know that anyone makes a nylon tab, but cordovan tabs are hard to beat if you use a tab. I've used calf hair tabs, but they wear out quickly. Cordovan tabs just keep getting better with time. I'm not sure they can be worn out! My oldest one is about four years old and going strong.
I know this won't help you decide between glove or tab, but maybe if you pick one or the other this will be helpful. I like tabs for lighter bows, but the Big Shot works great for a heavier draw or where finger pinch might be an issue.