I only rode my first coaster back in February of this year, and since then, I've been to Cedar Point and Sea World Orlando.
As for my favorite, I can't say anything other than Top Thrill Dragster. I know it's a bit typical to say so, and I know I will get many a Kingda Ka fanboy in my face, but I say it nonetheless. There is nothing like the experience you get on Dragster, and I'm sad that that is so true. I loved Dragster, but it didn't seem as extreme as I'd hoped, and knowing that it is, for all intensive purposes, the most intense ride in the world, is not comforting. I did not get much out of Millennium Force, though I have heard great things about it, and I was quite disappointed.
Kraken is probably my second favorite, and the coaster I've ridden the most. Yes, it has the typical B&M multi-inversion layout for the most part, but it was also my first coaster, so it holds a special place with me. Well, Manta is an interesting ride, but the position you are in becomes a bit uncomfortable after you've been stuck just outside of the station for ten minutes because of technical difficulties.
Maverick, I also heard great things about, and I can say that I like the drop, but everything afterwards was just painful, as the restraint was just too tight and killed my thighs on every turn. The queue line wasn't fun either, and the millions of dead flies all around didn't help.
Mean Streak also holds a special place with me, as the only coaster to ever make me wish that I had been hit by a truck in the parking lot instead of ridden. Fun ride, but it threw out my back and pulled my ab muscles. The lap bar was incredibly loose, and I found that I was banging back and forth between the bar and the seat. I would be perfectly happy if they would just burn the damn thing to the ground and build fresh with a GCI.
Gemini and Cedar Creek Mine Ride were great disappointments, but then again, I didn't expect much out of the latter. Gemini was only running the blue train, so the racing factor was gone, and it was just painfully rough.
And on one ending note, is there some magical place in this world where nobody screams and throws their hands in the air on coasters? I'd like to move there.