vstsynthfont is bundled with BIAB. it will load soundfonts which are availlbe free - a nice one is timbres of heaven.

however read Peter Gannon's sticky post 'no brainer'. It will tell you how to download the TTS1 GM soft synth. lots of people will tell you its old and out of date - yes it is old - but lots of us like it.

according to Dr Gannon it's the synth PG use to test design and balnce their midi styles so it can't be that bad.

try the TTS1 and see if you like the sounds. it might be what you are looking for and its easy to install and use. once you've donwloaded and installed it BIAB will find it automatically and all you have to do is choose it as the default synth. its easy to have a go and see what you think.