Pleasuredome is for all my roms/CHD needs.
I can't believe how easy
it is to maintain a good ratio there.
I always compile the MAME binary myself as it's the easiest way to go when using the diff update patches posted regularly on mamedev.
And last but not least, EmuLoader.. YEAH.
I'm glad I got myself a 1TB drive, a full MAME 0.130u4 set is friggin' huge (162GB).