Take this with a grain of salt, because I liked Twilight Princess (which has some pretty fun set pieces once you get out of the cutscene-heavy stuff--the duels on the bridges and the defend-the-cart-on-horseback scene are both favorites of mine because the horse archery works way better than Ocarina's did).
Boom Blox and De Blob are both a lot of quick, zany fun, with the added bonus that Boom Blox will do more for your ability to finely control the Wii remote than any other game because it uses motions you already know how to do in real life (as one of the game modes is essentially Jenga).
I can't get enough of Metroid Prime 3.
Mario Kart is kinda fun but I find it very hard to steer to the extremes consistently while holding the controller in midair.
I'm fairly sure the Guitar Hero series is much better supported on the Wii than the Rock Band series, and GH3/World Tour are both a lot of fun with some rocking set lists.
Oh, and the Strong Bad DLC games are a heck of a lot of point/click fun for $10 per.
Things I hated:
Any minigame collection.
Metal Slug Collection (needs better controls)