Definitely the looping or wooden. For both of them, It's not hard at all to get good excitement from them. The looping coaster is slightly easier though.
Well for me it's the steeplechase and the multi-dimension, You should really only use the multi-dimensional in roller coaster maker so you don't have to deal with time limits and frustration. The steeplechase is boring in terms of elements and you can't really bank turns. I got only one steeplechase to 7.11 excitement and that is it! Don't recommend using either type.