My brother (one of them) had a Genesis back in the day. I had a Dreamcast. We're all big gaming advocates, but those were some of our favorites (well, among those that didn't have Nintendo's logo on them somewhere).
And without the Dreamcast, I'd have no clue about the greatest fighting game series of all time: Soul freakin' Calibur. "Thank your Sega, kids." "Thanks, Sega."
First with 32bit graphics (32X)
First with downloadable content (Genesis)
First color backlit handheld (GameGear)
First 128bit Graphics (Dreamcast)
First true online gaming system (Dreamcast)
First system to use discs (SegaCD)
Looks like theres a LOT that gamers should be thankful for from Sega. Just because they weren't huge successes in some cases, it doesn't mean thta credit should not be given where credit is due.