Welcome to the forum. I'd have to favour Roy. Below, is a thread from the General forum last year that you may find interesting: http://www.boxingforum24.com/showthread.php?p=16656398 :good
Probably a topic for general given that I "believe" both these guys are still active. But I have a hard time seeing a prime Roy losing to almost anyone at 175.. I don't know.. Maybe I'd favor someone like Spinks or Charles over him. But even so it would be marginal at best.. Kovalev is an absolute beast however.. He's won desively against everyone of his victims and usually in brutal fashion.. But my one hesitation In picking him over jones is that he still needs to beat someone better than Nathan cleverly or a 50 year old Hopkins to convince me that he'd conquer RJJ..