I don't really keep track of the coasters I've ridden, and I only rank them from 1 to 3, so I've never bothered much with a top 10. But after reading this thread, I think I should at least try to narrow down the ten best coasters I've ridden. Note that the ranking might be based on rather hazy memories from many years back, so don't put much faith in it being accurate (even for myself). And there's always the odd chance that I've simply forgotten some coasters I've been on.
1. Helix, Liseberg. Technically the best coaster I've been on. Big, fast, has airtime, great views, snappy transitions, funny forces in all directions, and even an actual helix. It's great fun, well engineered, and highly enjoyable, and therefore nabs the top spot.
2. Formula Rossa, Ferrari World Abu Dhabi. This is where the ranking starts to get difficult, but because of that awesome launch and the whole "whoa" feeling of the ride, it gets the #2 spot.
3. Piraten, Djurs Sommerland. Forceful, has airtime, great fun. Been a while since I rode it, though. But I seem to remember having a blast.
4. Expedition Everest, Disney's Animal Kingdom. How do you even rank such a coaster? From the coaster ride alone? Relying purely on forces, what you would feel if you rode it with your eyes closed? If so, this would be a fair bit lower on the list. But Everest is so exquisitely themed, so creatively built and impressively engineered that the coasting bit of it is only a small part of the total experience. The effort put into this ride, from decorations to throughput to the audiovisual on-ride experience, earns it a place in the upper half of my top 10.
5. Balder, Liseberg. Catchy music in the ride station. Great throughput, so you don't have to wait for long. And one heck of a ride, rain or 'shine. A well-built wooden coaster that does not seem to get worse with age (I'd also like to use this spot in the list to lament what Thundercoaster has become over the years - it'd easily be top three if it still rode like I remember it).
6. Stealth, Thorpe Park. Similar to Formula Rossa above. A great rush of a launch, but this time with a great view before a quick and thrilling plummet back towards the ground. Does not seem to have the best capacity out there, though, I had to wait more than an hour to ride it. Then again, I did visit the park during a bank holiday, so it was probably just the sheer number of people that made the waiting time so long.
7. Dragon Challenge, Universal Studios Islands of Adventure. Two similar coasters, ridden back-to-back, occupying the same area, with the same queue line - yep, I'll rank them together. If I can't distinguish the ride experience of one over the other, no point in ranking them separately. I found it a really fun and pleasant coaster, with an impressively themed queue line. Shame about the lack of duelling, though. And for the record, Hulk was torn down for refurbishment when I visited the park, hence why it's not found in my top 10.
8. SpeedMonster, TusenFryd. Maybe it's clinging on to the top 10 for nostalgia reasons? Or that I haven't really ridden that many coasters, so it kind of deserves the spot anyway? Anyway, I still enjoy riding this coaster, which was the first one I did with a launch and with inversions. It looks good too, and has a better setting with the terrain and the park entrance than most coasters out there.
9. Nemesis Inferno, Thorpe Park. Another one with a 90-minute waiting time, but I remember it being a fun ride in the end. Inverts are fun, generally. Or maybe it's just B&M Inverts, I wouldn't know.
10. Den Aller Minste, TusenFryd. This is such a ridiculous little ride that I can't help personally liking it better than Lisebergbanan, Hollywood RRR, Seven Dwarves Mine Train, and the few other coasters that could have nabbed the number 10 spot if I didn't have such a hard time ranking them. Sure, these rides probably ride much better than Den Aller Minste (also known in the past as Teeny-Weeny, for reasons unknown - the park never used that name), but the whole package of it is so quirky and funny that I still favour it over those overall. I mean, the coaster is so tiny it looks like you could just pick it up and walk away with it! There are two pairs of friction wheels in its entire lift hill, which lifts the train to shoulder height or so! If the coaster was removed, it wouldn't even leave room for a tennis court! Its queue line is five meters long! It's just so adorable, and that makes it one of my personal favourites. For those reasons, it's likely to stay in my top 10 for a while, and if it ever drops, I'll consider reserving the 11th spot for it.
Also, my top 3 "dubious creds", which some people would count and some people wouldn't - I solve it elegantly by listing them in a separate list.
A. Harry Potter and the Forbidden Journey, Universal Studios Islands of Adventure. A really fun and well-themed ride. Somebody put a lot of love into this one, and the result is a really thrilling one. I'm not too thrilled about the giant spiders (okay, fear is related to thrill, so maybe), but otherwise it's a really solid ride with what might possibly be the best queue line ever.
B. Harry Potter and the Escape from Gringott's, Universal Studios Florida. Also really, really fun, but I'd rank it a smidge lower than its cousin across the studios lot. The part of the queue going through the main bank hall blew me away completely.
C. Bobbanen, Kongeparken. It's an alpine coaster, and it's fairly long. Good fun to ride, although if you heed the signage and stop before the station, you'll have a hard time getting it going again. You must slowly scooch the cart into the station to disembark. The lift hill is also a little tiring because it's fairly steep, lasts for several minutes, and there's no back rest. Great little ride, though! Also, it's the last of the three rides on my "dubious top 10", hence why it's not a top 10 list yet.