I guess mine would be Liquid Gold on the Micro cause when you get on a roll, you can keep retriggering the freespins and you can actually hit the higher paying payouts from time to time. You can't retrigger the freespins but once, i hit the freespins, completed, them, and did that 4 spins in a row.(mind as well been a retrigger)
RTG, Its got to be Golden Lotus Lately cause you can win a good amount of freespins during the gold lotus bonus round and i see that 100x bet bonus in there all the time (bet i have seen it 50 times, funny thing is i have never hit it!) And the white lotus, i like the 3x-5x win multiplier and can retrigger easily sometimes.
Rival, it would have to be scary rich2 or maybe switch in time, or maybe even So 80's. When they are hitting good, you can do REALLY well, if they are hitting bad, it could be forever before you get the bonus rounds.