OK, I made a decision ... and voted Beatles. I realized that my earlier statement was the key to the answer...
SinisterMinisterX said:
If the Beatles had stayed together just as long, we'd have a more valid comparison.
In other words, as things stand right now, it's a tie. But it took the Stones 25 albums over 42 years to achieve this tie, while the Beatles only needed 11 albums over 7 years.
Or: the Beatles broke up in April 1970. The Stones have had over 38 years to surpass the Beatles' legacy. And all they've been able to do is reach a tie.
What if my "if" in the quote above had been true? Let's just imagine (pun intended) that the Beatles had had one more decade of making albums together, until Lennon was murdered. The mind boggles at what they might have accomplished. And with another decade, they'd clearly have left the Stones in the dust.
Evidence? That's hard to come by for a hypothetical situation. But let's consider Top 40 singles by Stones vs. the ex-Beatles from April 10, 1970 (the day the Beatles officially disbanded) to December 8, 1980 (the day Lennon was killed):
Rolling Stones: 14 top 40 singles
John Lennon: 7
Paul McCartney: 29 (includes Wings) (or 3 without Wings)
George Harrison: 12
Ringo Starr: 11
Even discounting Wings singles, that's 33 for the ex-Beatles - over twice what the Stones got in the same time period.
Source: The Billboard Book of Top 40 Hits by Joel Whitburn, 8th Edition. Whitburn is the official historian of Billboard magazine, and the Billboard Hot 100 (which is the source chart for this book) is generally considered to be the chart of record for singles in the US.
If the Beatles had continued, this discussion wouldn't even be happening. Every other band, including the Stones, would be an also-ran.