Out of curiosity, what are the most common brand items in the Sphere?
Wow, that's a pretty hard question to answer, but I'll give it a shot... But you have to remember that this is based on all the sources I used. Nothing has been weeded out except the stuff that couldn't exist.... And to get on the list, it has to be present in at least 4 Houses (Great or Lesser)
Mechs
Archer (DC, FWL, LC, P-TC)
Griffin (FS, FWL, LC, P-TC)
Locust (CC, FS, FWL, LC, P-MC, P-OA, P-TC)
Marauder (FS, FWL, LC, P-TC)
Phoenix Hawk (DC, FS, FWL, LC)
Stinger (CC, FWL, LC, P-MC, P-OA, P-TC)
Wasp (CC, FS, FWL, LC, P-MC, P-OA, P-TC)
Aerospace
Lightning (CC, FS, LC, P-OA, P-TC)
Sabre (FS, LC, P-MC, P-TC)
Conventional
Note - Anything with a # after it, means that it's components are produced by various manufactures.
APC - Hover (CC, DC, FWL, LC) #
APC - Tracked (CC, DC, FWL, LC, P-TC) #
APC - Wheeled (CC, DC, FS, FWL, LC) #
Behemoth Heavy Tank (CC, Terra, DC, FS)
Demolisher Heavy Tank (CC, Terra, DC, FS)
LRM Carrier (CC, Terra, DC, FS, FWL, LC) #
Manticore Heavy Tank (CC, DC, FS, LC, P-MC)
Pegasus Scout Hover (CC, DC, FWL, LC)
Scorpion Light Tank (CC, DC, FS, FWL, LC)
SRM Carrier (CC, Terra, DC, FS, FWL, LC) #
Vedette Medium Tank (CC, DC, FS, LC, P-OA, P-TC)
For individual components... That's going to take me a little longer... Give me a bit and I'll be back with a list.