Camouflage: There's an Excel spreadsheet linked on
the wiki with
user-tested baseline camo values
as of 8.1. Keeping that in mind...
No data on the T-15. I suspect it would be close to the values of the 35/38/38nA, if there are any parallels to the Locust vs. M3 Stuart figure comparison.
The T-25 is significantly worse than the PzIV, especially when moving. The PzIV's stationary values are good enough that I think it justifies putting two crew on camo and using a net.
The T-25, since I didn't leave an open equipment slot for a camo net, should probably just hide in the back a bit, then dash in and out to shoot. Its view range penalty means that stationary sniping isn't going to do it very well (plus it's meant to drive fast anyway), and blundering around in the front line it is very obvious (and again, lack of view range unless I drive straight into enemy lines).
A camo net might help the Tiger and Panther. They don't help themselves very much. (Everybody takes a big camo hit when they fire, of course.)
The Maus has a hilariously low inherent camo value, just slightly above nothing at all.
The Pz S35 has a surprisingly high camo value, enough that I might consider putting the crew on camo instead of repair (as the tank has either taken a lot of non-penetrating hits and survived, or been totally cored out by a Tier V and died immediately). Might do well to use it as a defensive ambush tank.
The M4, Jumbo, and Easy Eight have comparable values... right between the PzIV and the T-25. I've been using a net on the M4, but didn't with the E8.
The A13 Cruisers (either flavor) don't hide very well at all. The Covenator and Crusader do.