As a family our fave is IASW because my daughter's jaw is dropped the entire time and my husband and I just love to watch her love it (she's 20 months).
My personal least fave is Splash because I hate drops but everyone I'm ever at MK with ALWAYS wants to ride it so I suck it up and I hate it every time. Luckily my husband doesn't mind skipping it so when it's just our immediate family I get out of it.
ETA: You didn't share, OP!!! What's yours???