I didn't think the Amiga version of Street Fighter II was bad enough to rank here. Now.... Dangerous Streets.... THAT was a seriously terrible game! Why the heck would ANYONE think this game would help sell Amigas??? I think people would have paid more for the Magic Packs, had they left this title OUT!
Days of Thunder was indeed the worst commercial racing game on Amiga. No doubt about it. ;-)
The best racing, of course, is Stunt Track, with two linked Amigas. Especially if they're lightly souped up to pick up a little extra frame rate. (My 1200/030 was perfect for hosting the race, and a standard A1200 linked made for an exceptional combination. Unfortunatly it seems to get unfriendly with 040 and 060 stuff, though.)
Though Indianapolis 500 deserves an honorable mention. It's dated by modern standards, but it blazed the trail for a long line of incredible Papyrus racing titles, and still has better drive dynamics than half the modern budget titles.
As for Speedball II... I'll still defend it. It's not quite as perfect as I remembered it, but man, it's still plenty playable, and fast, for the amount of things going on. A good choice for a retro night.
Nuclear War and North & South are both excellent. I'd also like to add a couple lesser known titles that have provided a few hours of amusment years later....
Armageddon Man -- nothing like sending a letter of support to Libya in regards to their missle attack on Canada. And the cat wagging it's tail as the display shows the bombs sailing across the continent...
Conflict! -- Who knew being an Israeli Premier could be so fun? (Sour relations by creating an international incident)