I agree with the horseshoe. It's an underused and usually undervalued element. My SoF has one right up close and it actually has a huge bearing on the value of the upper playfield drop targets. Some of my Sterns like Nine Ball and the incoming Ali have them too. The one on Cheetah is killer due to the closer upper flipper.
I always wanted to like vari-targets, but they never seem to feel all that great to hit.
Captive balls on the other hand are awesome! I love any type of newton or captive ball effect. Some feel really great and, when combined with great audio in newer games (thinking IJ), the feeling of really smacking a good newton ball shot is pure heaven.
I also love drop targets that can be swept. Thinking Space Shuttle, Quicksilver and other classic Stern.
Roto-targets on some EMs are also great. The fan type like Spin Out or Buckaroo are my fave.
And yes, spinners all day long.
I think I've listed just about every major playfield feature now
Unlike your buddy though, I can totally get into games with zero inlanes and no pops. Lots of my EMs have no inlanes and require great nudging... and I loved my Space Station. Shadow has no pops and it's a fantastic game. In fact, I tend not to like pops because they rarely do anything good except just bang around the ball for a few seconds. At least on older machines where they were placed in unique locations, there was a lot of strategy on how to play off the pop bumpers to help hit switches or drop targets that were otherwise hard to reach. Stern Stars, Joker Poker, Meteor, Frontier/Eight Ball all come immediately to mind. But, on most modern games, I could take them or leave them.