Tunney and Greb need to be thrown in as well. It's really tough to say which division is historically the deepest considering the long history of the sport. LHW does tend to get left out behind HW, MW, and WW when talking about the most storied divisions. LW, FW, and LHW seem to get comparable amounts of prestige. Then BW and FlyW are at the bottom. That's what it seems like to me, anyway.
I think BW is hurt by the fact that it hasn't had a lineal champion since hte late 80s, while FlW has had the opposite problem: it's had a lot of trading off of the lineal belt.
That said, don't sleep on BW and FlW. In terms of talent, they're plenty stacked. In addition to old time greats like Wilde, Puerez, LaBarba and Villa, you have guys like Harada, Choinoi, Canto, Chitalada, Chocolatito, Pac, Arbhachakov, Venice Bhorkorsor, Pong, Betulio Gonzalez, Kingpetch, Marc Johnson, and Accavalo, among others. THat's not even gettign into the likes of Eder Jofre, Harada (again), Canizales, Panam Al Brown, Sixto Escobar, Rafael Marez, Manuel Ortiz, Olivares, Zarate, Jeff Chandler, and many others at BW.
A lot of guys. Less dominance, but lots of talent.