Have you considered choosing 49 games and then having a flash cart?
I do feel you could build a collection of 50 or so games and have a ton of stuff to enjoy. The "must haves" will vary from person to person. I grew up with spiderman and xmen arcades revenge, so I'd need that one, but I wouldn't expect anyone else to need it. Like wise, theres lots of popular stuff that just doesn't do much for me. Castlevania 4 for example, just dont care for it. Most people would probably say it's essential. So yeah, if you want to pair down, have a look a what you got and think about it, what have you played recently, what havent you touched in a while? Also, dont forget you can always get something again if you regret selling it. Personally I've gotten rid of a lot of stuff and am perfectly happy with it.