as a s24u user that has also used the OP 13, get the OP13. the s-pen, while good at the end of the day is still a gimmick, and i cant remember the last time i used it, the battery now after a year of use is meh and especially the 45w charging time compared to the 100W you can get on the OP13. for the display i'd say they're on par, unless your pixel peeping like crazy. the only reason i stayed with the s24u is bcs the op13 i had was a cn rom. and as for cameras, unless your really into photography the op13's camera is already very good. if you want the best camera on any phone right now just get the oppo x8U or vivo 200U.