Overall, I'd say the 3 "best" albums in 3 years goes to not just the most critically acclaimed, or the biggest selling, or the most timeless (as in STILL selling to an ever growing multigenerational fan base) ....but a combination of all of the above. (especially the last one!)
That would be The Beatles.
Second would be Zep.
Pink Floyd runs a strong 3rd, but no one comes close to the longevity of the Beatles and Zep. The bulk of their most fervent fan base is comprised of the folks who were too young to have ever seen them live, much less ever stood in line out front of record stores on the day of release of any of their albums. In their first decade, their 3 albums were certified only 1x platinum, if even that, and several have since rocketed to 10-20x platinum! IMO, standing the test of time is by far the greatest accolade for any recorded music.
No other albums listed in this thread have sold more, especially a decade after initial release and beyond. Not even close. And for 3 albums in 3 years...in Zep's case, if you take their 1st, 2nd, and 4th albums, they are certified a combined 44x platinum in the US alone. For the Beatles, from Revolver to the White Album are certified 37x platinum...and the White Album counts twice for being a double album (otherwise they would be 22x Platinum) . In pure units sold, Zep's 3 even crushes those!
For me personally, the White Album is likely my least favorite from their entire discography. I actually consider it more like a couple solo albums backed by the rest of the Beatles. Lots of (IMO) throwaway material on there. Coming straight from the heart, I would put Rubber Soul, Revolver, and Sgt Pepper as my 3 for them.