Hands down - Malkin. He will be a 100 pointer year after year, and Horton tops out approx. 80. Playing with Crosby beats Jokinen, not to mention the studs on PP1 blueline - Whitney/Gonchar.
I think you also have to consider injuries. Horton has been a bit of a band-aid boy and plays a rough brand of hockey, thus more injury prone. Keep or get Malkin!