I support most things except Yet another transport system.
Nothing annoys me more than seeing another piping system that I have to try and disable.
Buildcraft - Possibly the strongest piping system if you use it right (LP Makes it insanely good)
AE - Basicly LP with magic blocks and turned up to 11
RP2 - Slow and clunky only good for systems with no though
PR - A Shitty logistics pipes
MFR - Interesting has limitations and some of the best enchantment handling sorting
GT - Simple pipes some handy sorting machines.
Thats just off the top of my head but I can almost bet there are more.