I really like Williams games from the late 60s and 70s, despite all the flack they take.
Pointy people and psychedelic colors don't deter me. Christian Marche was definitely different than Roy Parker, but that doesn't mean the gameplay is bad. If anything, the simple style Marche used makes restoration a heck of a lot easier, which is aces in my book.
A lot of their games allow you to collect the bonus during the ball instead of after the drain, which gives you something to keep shooting for instead of maxing the bonus out and then just waiting to lose.
Lots of save gates, save posts, ball return kickers, etc. give you that sense you can get some protection going and then when you think you're "safe" you lose the ball anyway. It's nice having goals that give you a false sense of security.
Pop bumper forests keep the ball nice and lively, and pop bumpers between the flippers are awesome for making desperate saves and "Oooh, ah!" moments when the ball defies gravity, looping around the bumper and right onto your flipper.
A lot of Williams game have some type of random bonus award that can allow a novice player to beat an experienced one. That might be bad if you're super competitive, but if you want to get people interested in the game it's really a nice feature, since it helps those players feel like they have a fighting chance and aren't just going to get beaten over and over if they play with you.
More drop targets would have been nice (Big Deal does have drop banks for what it's worth and several games have single drops), but not having them doesn't make Williams machines "not pinball" as some people claim.
I like working on them. I really "get" Williams start-up process, and I can find problems easier than on a Gottlieb from the same era.
I also tend to favor an underdog. If the majority only want Gottlieb wedgeheads, that's great because it leaves more Williams pointy people for me.