I'm actually partial to the Roland VSC (Virtual Sound Canvas). It does GM2 and GS. It has the SC88 Pro-stuff as well. Patch files, etc are already setup for BiaB. It used to be included (for free). The setup files are part of my BB2010, but apparently those don't play well with W8.1. Fortunately, I have a VST version still working (I dumped the DX stuff long ago). I have issues loading it into BB2015 (?) directly, but can pipe midi to it using MidiYoke (which does install after using some compatibility settings) via VST exe shell for the VSC.

The CW-TTS1 is more programmable (FX,etc) and does GM2 but I think it lacks the extra Roland soundsets. The TTS1 does load into BiaB2015, but is natively DXI, though it can be wrapped into a VSTi shell, which is the better way, as DXI support is disappearing.

As noted, these are just GM/GS sounds, so not considered 'pro' but more than adequate for composition stuff. I use RBand/Sonar/FLS and my own VSTi's when a song is worth the effort to 'finish' with better samples/instruments. Though the whole export midi/audio is a bit tedious which is the plug for RBand.

I'm actually pretty bummed with the SampleTank/AmpliTube BiaB stuff. They are just demo's and while nice are pretty pricey. The real downside is that they scatter files all over the place and don't clean up after themselves well, leaving IKM junk scattered all over including the registry, so I don't even consider installing the demo's anymore as they are more trouble than they are worth. The IKM copy protection stuff is just a real PITA (imho).

It's been awhile since I've played with SoundFont's (given their age/legacy). While not quite as PnP as the VSC, they are more versatile, though require more work (searches, DL's, comparisons, etc) and setup. Basically, they are reduced feature set SampleTanks.