Tough one. The Afterburners have such a massive difference in ride quality between them all.
Inward facing:
Bottom of the list is Vortex. I hate that ride. It's just nausea inducing and not at all fun. Something to do with being very weak I think.
At the other end of the scale is Beach Party at Coney Beach. That was incredibly intense and superb fun. Brilliant ride.
Eagle's Claw is okay, it's good fun, but nothing special - same with the Afterburner at Brean. Good, but not great.
The Streetfighter models are excellent fun, with some brilliant floater airtime on them. Freakouts I've never had a good cycle on, but they show potential - they just suffered from "noooo! Give me more" Thorpe syndrome.
Outward facing:
I've just done the two.
Flip was really good fun, good ride, good cycle, good mix of forces.
Maelstrom is possibly my favourite flat. I love the floater, followed by the excellent high-g on the bottom of the swing. It's just a ride that suits me perfectly.
So I need more experience on the outward facing ones. Beach party was different to Maelstrom, but came close in my opinion to being as good in terms of "I loved that". All the other inward facing ones I'd rank below Flip Flop (but not massively).
However, re-ride is where the outward ones win. The inward ones always leave me feeling a bit queasy (or just plain ill in the case of Vortex). SO I tend to just ride them once. Flip Flop and Maelstrom I could re-ride all day
So outwards takes it