Charlie Parker(sax), Chet Baker(trumpet), Thelonious Monk(piano), Tal Farlow (guitar),
to which I'd add Max Roach (drums), and Charles Mingus, (bass)
but I think I'd replace Chet Baker with a hotter trumpet player, like Dizzy Gillespie. Or I might replace Bird with Zoot Sims, as a match for Baker. Add Gerry Mulligan (bari sax) to the latter lineup, of course.
This is bringing back memories for me, of the 60s and Downbeat magazine delivered to my house, "The Collector's Jazz" books by John Wilson, and late night listening sessions -- "bllindfold tests" and all -- with my high school nerd buddies.
Actually, there is no such thing as a perfect ensemble, either in instruments involved OR in the players. Or rather, there's no such thing as ONE perfect ensemble. I've heard the most amazing agglomerations of instruments work well and "standard" ensembles suck harder than a Hoover. It all depends on the song or tune, the style, the players, the audience, and the moment.
In other words, it's all magic anyway.
Personal favorite ensemble: Geroge Stephens, 6- and 12-string guitars, vocals; Pete Kraemer, guitar, dobro, bass, banjo, autoharp, vocals; and Bob Clayton, guitar, banjo, mandolin, banjo-mandolin, harmonica, and vocals. We're called "Sidekicks."