Here are the flavors I've tried, and what I thought of them!
Butterbeer soft serve--This was the first one I tried. Very creamy, strong butterbeer flavor. I like it better than regular or frozen butterbeer, but ice-cream-wise I still prefer the hard-packed ice cream at FF.
Salted Caramel Blondie --the best out of all that I tried! It has a very strong flavor, soft chunks of blondies, and is very creamy and sweet.
Earl Grey and Lavender --Loved this ice cream. If you like vanilla you will like this. It's a subtle sweet cream ice cream with a light floral/lavender flavor. Didn't taste the tea part. However if you aren't the kind of person who likes vanilla ice cream, you will probably find it too plain.
Apple Crumble--has the same kind of cinnamon-apple flavor you would get in oatmeal, with the same dehydrated bits of apple. It was good, but not great. I kept thinking of oatmeal instead of apple pie. Not saying it's bad, but I'd rather order one of the three flavors above.
Sticky Toffee Pudding- Has a basic light butterscotch flavor overall, with bits of chewy pieces in it. Kind of like a watered-down version of the Salted Caramel Blondie flavor. I would definitely recommend ordering the blondie flavor instead. Better yet--go have real sticky toffee pudding at the Leaky Cauldron!