This ranking includes all theme-parks I've been before:
Austria:
Prater
Belgium:
Bobbejaanland
Walibi Belgium
France:
Disneyland Paris
Parc Asterix
Germany:
Europa Park
Phantasialand
Holiday Park
Heide Park
Tripsdrill
Movie Park
Italy:
Gardaland
Netherlands:
Efteling
Walibi Wavre
Favorite Coaster:
1. Space Mountain (Disneyland Paris).
I've never been in theme-parks outside of Europe, but I've riden many great rollercoasters, so it's a pretty hard decision. But the suspense and theming of Space-Mountain is incredible. The "Launch", the layout, the effects. Pretty amazing (but I liked the older Jules Verne-style even more).
2. Colorado Adventure (Phantasialand)
Big Thunder Mountain has the better theming but Colorado Adventure is the better ride. I love mine-train coasters.
3. Tornero de Zeus
What a weird, great ride. So rough, so much fun. The greates wooden-coaster I've ridden so far.
Honorable Mentions: Wodan, Rock n' Roll Coaster, Blue Fire, Expedition Geforce, Karacho, Oziris
Favorite Darkride
1. Fata Morgana (Efteling)A beautiful dark ride. Not just a boring "Pirates of the Caribean"-Clone like the one in most other parks (one of the worst the Europa Park version) but a ride with story, heart and adventure in it. A beautiful ride around the arabian nights. Yes, i like it even more than the disney masterpiece.
2. Pirates of the Caribbean (Disneyland Paris)
A classic. Great storytelling, beautiful sets and a great adventure vibe... and of course a great soundtrack.
3. Maus au chocolat (Phantasialand)
The best interactive dark ride so far. Great fun.
Special Mention

hantom Manor ( it's very sad that Disneyland Paris doesn't invest more in this ride. The effects are outdated and a few doesn't work anymore. It would have been in the Top 3 if it wasn't in this bad shape the last time I rode it (2013).Honorably Mentions

roomvlucht, I Corsari (the underwater effect is amazing)
Favorite Waterride
1. Teufelsfässer (Holiday Park)
That was a great water-ride, sadly they rethemed it. The river ride to a demonic mill full of devils was great suspense, and the ride itself was a great thrill too (Double drop, backdrop in the darkness, great length)
2. Chiapas (Phantasialand)
Newest waterride technology. Great last drop (with airtime in it), good length and great theming. A perfect waterride
3. Badewannenfahrt zum Jungbrunnen (Tripsdrill)
What a great idea, a waterride through an old castle in search of the fountain of youth. A clever, original idea, a good layout and a great last drop.
Honorable mentions: Wildwasser II from Heidepark (doesn't exist anymore), Menhir Express, Radja River (very wet), De Vliegende Hollander
Favorite Flatride:
1. Tower of Terror (Disneyland Paris)
A mix between dark-ride and freefall-tower. The theming is perfect, maybe the best I've ever seen so far (all the little details and Twilight Zone references). The ride is pure fun and thrill. Absolutely great. Really want to ride the Tokyo and the Orlando version of it (someday I will [yesnod] )
2. Mystery Castle (Phantasialand)
I hate Topspins, so I've never ridden Talocan, but Mystery Castle is great fun. Great theming and a good thrill-factor.
3. Breakdancer (Nearly every Funfair has one)
A classic.