I had similar requirements to yourself for the games. The thing is some (Pacman, donkey kong) are 4-way and others are 8-way. For this, I decided to go with the Mag Stik Plus which does 4 and 8 way by pulling from the top. There are others, but they are all controlled underneath somehow. I believe the mag stik plus isn't so good for fighting games though due to the short through. I'm not a great player of these though (but will have some). An 8-way works, but not great I understand - you hit the left/up diagonal and pacman / jumpman won't go up OR left and it messes up your game! I suppose the way to tell would be to play it on the keys or a gamepad in mame and see what it does when you press left/up together.
The buttons were the budget ones - £1.20 each I think.
I went for the mini-pac which seems to be the iPac but with trackball/spinner control also and simpler to wire. It also works out cheaper than iPac/OptiPac if you have a spinner/trackball as its all in one. Any joystick/buttons work with it (and the iPac (I believe).
I'll let you know how it goes though, I should get it all next week! I ordered from Gremlin. The price did tot up with VAT and postage but I didn't find any others any cheaper in UK though let me know if you do.