I truly love virtually every version of Fleetwood Mac that's ever seen a stage or tracked a tune. (The "faux" Mac stand-ins who toured in the mid-70s per some contract dispute might be excepted). IMO, Peter Green was arguably the best of the Freddie King guitar lineage (tho those who prefer Clapton, Santana, Knopfler, Mick Taylor, Stan Webb et al all have a case). From the get-go, Fleetwood Mac was special, IMO.
As stated earlier, I'd argue that Danny Kirwan is a sadly overlooked songwriter, player, and (perhaps first of all) arranger of songs for guitar. My first public guitar performance was my own acoustic arrangement of Kirwan's song "Dragonfly" (from BDP's preferred Kiln House line-up). I also believe that Jeremy Spencer is the living spirit of Elmore James.
As Mofi notes, the classic Christine, Lindsey, Stevie line-up can make a strong case as the best of the lot, because they do more things well than any other iteration. They truly are masters of a huge range of styles - from pure pop to blues (on the too rare occasions they go there) to punk to pretty much everything you can think of.
In the end, I listen to what my mood dictates. Songs like Man of the World, Black Magic Woman, Green Manalishi, and Oh, Well are all in regular rotation in my listening room. As are later albums like Tusk, Rumors, Say You Will, Tango, and The White Album. Along with mid period albums like Heroes, Kiln House, and (especially) Mystery to Me.
Lindsey Buckingham is such a bizarre and fascinating guy (not to mention otherworldly guitar player) that his stuff (both Mac and solo) is first among Mac members for me. My intention was never to dis Peter Green, et al, but rather to argue that Buckingham (first and foremost) and Stevie Nicks were not responsible Fleetwood Mac's "pop sell out" per the popular narrative we've seen repeated here. They certainly polished up the erratic blend of pop sounds that Mac had adopted after the departure of Green, Kirwan, and Spencer, but they didn't make Mac a pop band. That happened before they joined.
I envy Andrew in that I never saw the Green, Kirwan, Spencer line-up perform live. I do love the dozen or so live albums of that iteration of the band that I own. I also believe that the Stevie, Lindsey, Christine version is a monster live band. In the end, I don't want to toss apples in favor of oranges. I'll enjoy the whole fruit salad.