I've been to 9 parks, but my list still looks a little green:
Top 10:
1. Raptor
2. Millenium Force
3. Magnum XL-200
4. The Beast
5. Thunderbolt
6. Mantis
7. Loch Ness Monster (really just an Arrow looper, but still stylish, and was my first inversion)
8. Exterminator (Kennywood)
9. Jackrabbit (Kennywood)
10. The Racer (backward side, PKI)
I guess my list is still CP-centric, but I went to parks like BGW, PCW, and SFO in the late 80s/early 90s before they hit their modern coaster booms (and PKI pre-SOB), and I've been to quite a few parks (both Disneys, PCarowinds, SFEG *post Mr. Twister*) without top-10 quality coasters. Next month I hit IOA and BGT, so I expect the list to be upgraded a bit.
Bottom 5:
1. Raging Wolf Bobs (SFO)
2. Mean Streak
3. Steel Phantom
4. Twister II (SFEG)
5. Disaster Transport