That Mary J song is one song. Cam had more visibility in 05-08, or whatever year you want to name after 2001.
Cam has better solo work too.
The first charting track from 36 Chambers was a Method Man solo song.
Meth had platinum solo albums in 1994 and 1998 and a gold album in 2004. Plus a platinum album with Redman in 1999.
Cam had gold albums in 1998 and 2004, platinum in 2002. And the gold Dip Set double album in 2003.
Neither of their solo catalogs is strong as it should be based on their talent. Both their solo albums suffer from a lot of the same things. Inconsistent, too many filler tracks, too many pointless skits.
But Meth was more commercially succesful and was commercially relevant for longer, that's inarguable. When you start comparing group catalogs and classic guest appearances it start shifting heavily in Meth's favor.