Saturn, followed by the Turbo. I don't consider the Dreamcast a failed system, at least not in this part of the world. It was short-lived, and there are various reasons for that, but it was a success in North America while it was around.
The Turbo did indeed have games trickling in for a good length of time, but from a commercial standpoint, it was most certainly a failure in North America. Even from the beginning it was never successful here, and it only got worse as time went on. Both Genesis and Turbografx had games that held their own against or even surpassed anything on SNES; that wasn't the problem. It had very poor marketing, practically zero hype/recognition of even its flagship titles, and a general lack of retailer presence. By the time Bonk III CD came out, most Turbo fans had no option other than to purchase it via mail order, because most stores didn't carry that game and many didn't even have any remaining Turbografx stock left by that point. TTI never had the resources to properly manage the system -- after a decent (but brief) early push from them when they first took over and the Duo first released, the system languished badly. The Duo soon found itself in fourth place, behind Sega CD.