Depends on the definition of roller coaster. Anything with a loop is out, but I love wooden roller coasters like Gwazi at Buschgardens and one of my favourite rides is Big Thunder Mountain.
X2 at Sixflags Magic Mountain, California, it is a 4D coaster so the individual seats rotate 360 degrees when you are going around the track (so your seat does a 360 spin whilst going over the loop!) It is very scary but is my favourite coaster, I rode it several times!!