The single six is a must own relover, if there is such a thing. The single 10 is a head scratcher to me. Why try to squeeze in 4 more rounds into a single action of all things. You lose the ability to convert to 22mag. And SAs aren't meant to be high volume lead throwers. It also looks ugly. I guess I prefer a traditional 6 shot in a SA.
The sp101 would be a great option if the triggers weren't awful. Granted with a little work, the trigger can be improved all the way to mediocre.
The 617 is definitely the way to go. It will probably still need a trigger job and quality control at S&W is no better than any of the others. But once you get it up to snuff, it's awesome. Nothing wrong with 17s or 18s. But the stainless 617 is way more durable and you'll get a lifetime service agreement that won't come with a 17 or 18 (Or were some still made after 1989?).