I know that Oregon and Windsor both sell 25 ft coils of chain. Don't know about the other brands. I have used Windsor for years and like it.
I give up trying find Stihl saw chains online so my next choice is Oregon chain. My 550 Husqvarna I bought 2 years ago now came with semi-chisel Husq chain and it broke only half used up and the other ones, not sure what they was, they cut ok, but this new Oregon chain,(full chisel) is really cutting awesome, I forgot what full chisel cut like and the little holes in the drive link seams to be getting more oil on my bar, but I cant find 25 ft. chain rolls online all I see is 100 ft. rolls, maybe it requires more Sat. morning net-working.