Very hard to rank, I'd say:
1 WW3 (lyrical masterpiece, minimum of typical NL formula. Mac's flow on this album was ridiculous)
2 TOIEF (so many classic cuts, such a great moody dark vibe)
3 Street Life (this albums smells like the NO. Indeed BBTP's swan song, and such a good one at that)
4 Shell Shocked (brought down by too many stereotypical NL cuts like Nobody Make A Sound or Soldier Party. But it has some of the best songs in NL history: Slow Ya Roll, Be All U Can Be, Can I Ball)
The 96-99 era HAS to be the one above the rest, BBTP as well as DJ Darryl, K-Lou, Mark in Da Dark etc brought the heat usually. You could hear that BBTP were burnt out starting in fall 98 (around the Mean Green and Mia X albums)
However, there were many overlooked/underappreciated projects before (WCBB Vol 1, 99 Ways To Die) and after (Trapped In Crime, Last Meal, Good Side Bad Side, Streets Made Me) that deserve to be heard
Overall BBTP has to be in discussion for best southern producers OAT, I'm sure there are some above 'em (Mannie, Paul/Juicy, maybe Neptunes and Timbaland) but they churned out so many hits and hot cuts within maybe 5 years, it's ridiculous