My pet hate are loooooong games. Yawn. I have had and seen nearly hour long games, while this is a great personal achievement, it is definitely boring in a gathering.
Pinball is meant to be social and therefore quick multiplayer games are my favourite.
Recently loving Iron Man VE as it is very short ball times and a hoot in multiplayer.
In fact 95% of all my collection are very quick games like BBH, GI, Dr Dude, FT as an example. RBION being the odd one out.