If you get a G-Sync display then anything over 90fps starts to get very hard to notice. It's a really subjective thing, so it's difficult to say what you'll appreciate more, but for most people 90fps + with GSync is enough.
Remember that most benchmarks are taken at really ultra/very high detail settings too. Sometimes there are a couple of settings that have a big impact on performance without offering huge benefits in image quality. The GSync monitor allows you to dial up the detail settings, but still get smooth gameplay where that's your priority, while also dropping quality a little and getting extremely high frame rates on a different game... where it might be more important. GSync lets you prioritise either frame rate or detail on a game by game basis without having the wrestle with the limitations of VSync or put up with screen tearing.