basically a girlfriend who everyone has fucked b4 you but in a relationship is still %100 faithful. oppose to a girlfriend with a handful of guys but will cheat on you when she gets the chance
how is this a question? one is a good girlfriend (at least based on the minimal information given) and the other one cheats on you. it's like asking "who's a better roommate? a guy who got 3 blowjobs before he met you, or a guy who will stick his dick in your mouth while you're asleep?" the only way i can see this being debatable is if the good girlfriend literally fucked EVERYBODY before you. because, i'd totally rather get cheated on than be given AIDS.
My dad had a saying, "A buddy is a man who goes out on the town gets 2 blowjobs, comes home and gives you one." C/S, Rev J
option one, because I'm not hung up on numbers open relationship would not necessarily be a bad thing, but violating agreed upon terms of a relationship is not ok