Hello C.B.
I've had both, in lathes and milling machines.
There are very few negatives for either brand of lathe. When it comes to accuracy, they are equals. The two companies take a different view on what they want to produce for the public, but in the end, the machines will do very similar work. Both lathes are a good example of how to make a quality machine.
I happen to like the Taig better, and it's what I currently own, but was very pleased with my Sherline, too. Most of what I like more about the Taig is just personal preference.
If you decide on the Taig, just buy the lathe without the motor, and put your own DC motor on it. A good DC motor and controller can be had for around $100-125.
See the link below my signature. Almost everything on those pages were made with my Taig machines. Almost everything there could have been made with Sherlines, (some was).
You'll probably like whichever one you choose. They're both good.
Dean