I'd say there is much more available in the way of parts and ready-made solutions for interfaces etc, but as far as software goes I wouldn't say there's much need to change your current Mamewah/Mame setup unless you want really new games.
At Turnarcades we build basic functional machines and I'd just say go with what you will play most of all. A 2-player, 6-button layout covers most regular Jamma-originated games, with a start button each, 'credit' button and maybe a handful of admin buttons for easy launch game/pause/exit functionality. If you can stretch the few extra quid/bucks then plump for a 3" trackball and maybe a decent spinner, if that is your thing. If classic games are your thing you may want these, and with all the 4/8-way switchable and programmable sticks you don't need to have a control panel that looks like a dildo display shelf in a sex shop either.
Places like Ultimarc will provide high-quality parts with ready-cut/crimped looms and compact interfaces to make it all easy, so throwing together your own arcade has never been easier!