As Funkadelic / Parliament were a force that was spread across labels, produced so much music & evolved quite a bit over the decades it's tough to find a good place to start. Although this Focuses just on Funkadelic, specifically their 45s output on Westbound between 1968 and 1976, I do think this is a great starting point.
All the A and B-sides are here with a couple of things previously unreleased tracks, showing the evolution of the P-Funk from '68 through to arguably their peak in 1976. If you coupled this with the excellent ParliamentFunkadelic Live in Houston 1976 DVD* I really think you'd have a dose of magic from the Mothership that you'd never come down from, and you'd still have all the albums and album tracks/versions to discover! Amazing.
There's also extensive sleevenotes and some great pictures included with this CD - You really can't go wrong.
* DVD available as:
"Mothership Connection Live 1976" [DVD]"
"George Clinton - Mothership Connection [DVD]"