IMO priority is blocking UV damage and water intrusion. If left unchecked, water may gradually loosen the bond of the coating around the chip. If bare fabric has been exposed to UV for more than a few months, then fabric at that spot has probably deteriorated. Not an airworthiness issue, but does extend the life of the coating to fix small blemishes before they become bigger blemishes. If chip is recent, dab UV blocker on it, then color. If chip has been there for more than a few months, IMO a 2" round patch is prudent.
I always advocate using the same coating system that it is currently covered in. Mixing systems and products raises the odds of incompatibility if you or someone else later decides to refinish or refresh the coating later. Nothing more annoying than prepping to rejuvenate dope and having to sand off splotches of rattle can enamel. So, a little research will tell you what product to use.