How about four?
One guitar, or three?
Many fans of Rock music guitar playing consider the players who were the only guitarist in their band "the best": Jimi Hendrix (in The Experience), Eric Clapton (in Cream), Jeff Beck (post-Yardbirds), Jimmy Page, Billy Gibbons (ZZ Top), Eddie Van Halen, Stevie Ray Vaughan, the clown in Black Sabbath, etc. etc.
I on the other hand have a love of not the classic 2-guitar line-up (The Beatles, Stones, Rockpile, etc.)---good as that can be---, but of 3-guitar bands: Buffalo Springfield, Moby Grape, Fleetwood Mac in their Peter Green/Danny Kirwin/Jeremy Spencer period, and The Flamin’ Groovies in the Shake Some Action album era.
Three guitars is even more musical than two, and far more so than one. All kinds of little song parts are possible with three musical instruments, and Springfield and The Grape really exploited the possibilities. One guitar is so, well, 1-dimensional. Sure, on recordings the single guitarist in a band can recorded multiple parts, but "lead" guitarists rarely think in "song part" terms, but instead in "guitar chops" terms. Know what I mean?
I bought the first two albums by both Cream and Hendrix when they were released, and saw both live twice in 1967 and ’68. But the music of both got old pretty quickly, I losing interest after those albums. You may disagree. ;-)
Now, one guitar is fine if you have other musical instruments (bass and drums can be played musically, but they aren’t "chordal" instruments), such as piano and/or organ. Two of Rock ’n’ Roll’s most musical ensembles had both piano and organ, and only one guitar: The Band and Procol Harum. Those bands also had great songs. Coincidence?
If anyone has other 3-guitar bands/groups to recommend, I’m all ears.