I'm going to be controversial too, guys............. MAME has actually technically gotten worse features-wise since they decided to take an anal approach towards "accuracy" by dropping great features like the highscore-saving, and the AVI-recording support, and having people redo their entire config setup for each game again due to the switch to XML. Mr Stuart Campbell explained the situation much better two years back
than I could possibly do myself.
Don't get me wrong, MAME is good for emulating the odd interesting rare gem on occasion, but I just don't like the overly-serious approach they've taken of late. I rarely use MAME these days myself.