Gladiator got very good free spins
Only if you get the extra scatter symbol though (and even then there is no guarantee). This is one game where, when it first appeared it seemed to pay out a lot then died on me. Plus, when I played the pre-release demo at ICE, the RTP was definitely +ev LOL. You couldn't lose. Great game though - this is the one that upped the ante, IMO.
Kong could have been good but they screwed up the betting increments. Jumping from $2 to $5 to $10 to $20 is crap. Probably fine for low rollers but it doesn't fit with the way I like to play at all.
I think the "expanding scatter symbol" type bonus round is one of my favourites. I'd guess they nicked the idea from Novomatic's 'Book Of Ra' but Playtech now use it in at least 4 of their slots I can think of off the top of my head.
But Great Blue's free spins when you get the 23 spins at 10x with stacked wilds....awesome!