I can say the out of the box trigger in MY M85 is far better than any 642 I've tried. It's pretty awesome. I've heard same from others.
The Smith does have more accessories available, like laser grips and such, that the Taurus lacks. But, leather and aftermarket grips aren't hard to find for the Taurus. If it's made, it's made for the Smith J frame, though.
The only guns I've ever had to send back were a Phoenix Arms HP22 (self explanatory) and a Rossi M971 .357 revolver back to Interarms that had snapped a firing pin. If I have to send a Taurus back, well, I have 20 other handguns to shoot until it gets back. I ain't worried if it takes a couple of months. So far, though, I've yet to have a reason out of three Taurus revolvers.
I had a forcing cone crack on my M10 Smith once, but bought a barrel for it and had a gunsmith install it. I don't know if Smith and Wesson would work on a gun that old under warranty anyway. It's an early 60s production, back when they didn't have locks and built 'em with pride. Yeah, the Taurus has a lock, too, but it's in a much better spot and won't lock itself. If I bought a 642, a drop of locktite or super glue would accidentally get spilled on that lock.
I just kinda lost the key to the Taurus. Never had a problem with it in 6K+ rounds.
I don't know if many smiths mess with Taurus. I've heard it's hard to get parts for them. However, gun parts inc. lists all the models and parts. EVERYONE will work on a Smith and Wesson, so that's an advantage to Smith.