+1 for MGalaxy. http://www.mgalaxy.com

I have set up three multi-emulator systems, and only discovered MGalaxy during the most recent build. To me, its ease of setup felt like a revelation compared with the endless tweaking that Hyperspin and Maximus seemed to require. Everything is GUI-based and the tedious stuff like fetching artwork, gameplay videos, and game history is automated. The frontend screens look great, and the paid version (worth the $$) adds lots of neat themes and unlocks some useful database customization options.

If you want a more turnkey option for cabinets and control panels, check out Rec Room Masters. They make several different cabinets and control panels (one with a trackball, spinner, and separate 4 and 8-way joysticks), so all that is needed is a PC/Pi/game console and display. They also make cabinets which are customized for the X-arcade control panel. Not as cheap as DIY, but look and feel “professional” and save a LOT of time versus scratch-building or cleaning/modifying an old cab.