I had a feeling someone would ask me that, as Ive been asked before

Thats a tough question. Its like asking me: which arm do I prefer, my left or right?
They are both superb, top-notch amplifiers, though made by Sansui at different times.
I do like the fact that the B-2301 runs cooler, which is impressive for a 300 Watt beast that has no cooling fan. The BA-5000 tends to get quite warm after its been on a while.
In order to try and do a fair listening -*test*-('"), I should probably compare them using the same preamps and interconnect cables, etc. But due to all the stuff I have, its a bit of an effort to have to start swapping things around and connect either the CA-3000 or C-2301 to the BA-5000 or B-2301. The other thing to keep in mind is if both amps are setup properly,: bias, dc offset, electrolytic caps are still good etc.., otherwise the comparison probably wont be accurate.
Nonetheless, I suppose if I really had to make a choice, it would be the BA-5000.
Its has a very warm, pleasing sound, and of course, can provide tremendous power if needed. No other Sansui model is quite like it. It can be bridged to mono for 600Watts in case anyone has the desire to destroy the neighborhood
The B-2301 is great, but I think the BA-5000 is still The King.