Velocicoaster is a beast of a coaster, super smooth and extremely fun layout. Hagrid's is very very cool too but I prefer Velocicoaster over Hagrid's.
I haven't experienced that many coasters outside of WDW and Universal Florida, so mine would probably go to Velocicoaster as well. Woud LOVE to visit Cedar Point at some point!
I do have to give an honorable mention to Epcot's Cosmic Rewind, while the theme and attraction doesn't fit at all at Epcot (I promise I won't go into that right now), I can't deny the coaster is extremely fun and smooth. Very fun ride but the theme and placement just brings it down for me.