I had mixed results on my LJ with paining the fenders. Mine are starting to fade on my JKU and I'm thinking of getting the cheap-o amazon fenders so I don't have to keep messing with them.
Until I buy new ones, I have been using Meguiars back to black and that makes them look really good for a month or so.
U-drive 4pcs Black Steel Fender Flare Fit 2007-2016 Jeep JK Wrangler https://www.amazon.com/dp/B01G1GRQBM/ref=cm_sw_r_cp_apap_vjOYGX8tr5i1t I got these and they fit perfect and are the best priced ones I have found. The price is for all 4.
I would go with these ones to be honest. They are likely made in the same factory as smittybilt for almost half the price.