a lot of people like the aftermarket system, but some people, like me, like the stock look. the BIGGEST benefit to having a stock radio in there is people won't break into your car to steal your stereo. They don't care what brand the aftermarket HU is, I had someone break into my car for the durabrand unit I had in there...
1996-1998 TL radios plop right in, no modification to the harness, and they have a 6 disc option. the biggest problem with the TL radio was the fact that the 1996-1997 single cd player had bad laser problems, much like the G2 legend's BHG problem, it wasn't all of them, but it is a widely known problem. The TL radio, the 6 disc indash, also has a DIN connector on the back that can be modified [just buy a DIN plug from radio shack and there is instructions about wiring it up to accept the iPod somewhere on the site, if interested I'll dig it up for you] then you don't have to worry about the wireless crap to listen to your iPod in the car AND you have a stock looking radio.
There are plenty of people on the site that think the BOSE was very well designed in the Legend and sound great. Others, mostly audiophiles, say that the BOSE will never sound as good as an aftermarket system.
I say stick with stock, but thats just me.