The original GB is the only system I owned as a kid that I ever actually sold or got rid of, everything else I still own to this day. I sold the system along with all the games, manuals, Game Genie and a carrying case when I first started selling on eBay in '97. I probably had a dozen or so games for it with Kirby's Dream Land being the newest release I had bought. After I bought a Game Gear I barely touched the GB.
I remember in '92 or '93 my brothers and I were going on a 12+ hour road trip to Florida. As we were leaving town we made a final stop in Walmart. I was absolutely eat up with fighting game fever and there on the shelf was Fighting Simulator 2-in-1: Flying Warriors, which was pretty much the only thing resembling a versus fighter on the GB. I forced myself to play it on the ride down, trying to convince myself it was just as good as MK or SFII. Spoiler alert: it was dog shit.
There's a handful of GB games I owned that I might could genuinely enjoy today had I not sold my system. However, I can play all those on a PSP with a vastly better screen and controls than a GB, so I don't feel like I'm missing anything. I still own my GBA stuff but rarely touch it for the same reason; it's just better on PSP.