A few I have done many many thousand spins on and never got a single decent bonus
Jammin Jars
Fat Santa/Rabbit
DoA 1 and 2, I've defo done over a million spins on them (mainly 1) and never had 5 scatters or a wildline.
Napoleon
I know there are others too just can't remember from the top of my head.
What about Casinos, do you have lucky/unlucky ones?
Coral I regularly cashout, and have a few times pulled out £2k+ from a £20 or £30 deposit
Casumo I had my 4th largest cashout ever at, but it seems I either win big or lose in minutes.
Rizk had some good cashouts at
VeraJohn I was over 100% RTP overall when they closed.
LV Bet, can't win on, despite playing the same games as elsewhere.
William Hill, can't win a penny there.
L&L comes and goes. Mainly lose though, but keep playing as it has to change at some point and the rep is excellent.
Trada never won on.
Some WHG casinos I did ok on then stopped playing after the inevitable bonus ban, even though I had only used 2 or 3 in a year lol
SkyVegas have had my top 3 cashouts at, including a 11k one that came from a free 50p scratchcard!
Videoslots were by far the worst, I think my lifetime RTP was about 80% when I stopped playing there