Rice is unequivocally the best WR of all time, and it's not even remotely close. His abilities, stats, longevity, hands, everything. He's untouchable. But Montana only had him as a security blanket the first six years of Rice's historic career. Taylor was really good, 2 time probowler, but was a complimentary guy overall. He did have Roger Craig pretty much his entire career, however.
Brady, however, had Troy Brown, Deion Branch, David Givens, Reche Caldwell for the first couple years. After that, however, he had Welker & Moss for a few years combined, and Moss left just when Gronkowski was coming in. So, although he had a few years to start this career where he had scrubs for the most part, he's had the majority of his career with maybe the 2nd best WR of all time, or one of the best possession WRs of all time, or maybe the best pass catching TE of all time. And if Moss, Welker, or Gronk don't fit into those #1 slots on someone's board, they're certainly in the discussion.
It's close between those two for #1.