I don't have much Sega, was a late adopter in the 90's, but I've picked up only those games that I played and enjoyed over the years via rental, friends' houses, etc. and have kept the collection tight. About 6 titles to go, and I'm good with Genesis.
Another 4 games I'm after for the SCD, and done with that too.
I've always been a fan of the Saturn, but again, just keeping it tight; same idea, 3 more to go and I'm done.
Dreamcast is near and dear to me, and other than regretfully selling my Last Blade 2 about 10 years ago, I've got everything I want for the system.
I may not be a Sega diehard, but there are things I appreciate about the company and their library, especially DC era.