Sleeping Baby Productions
Sleeping Baby Productions (SBP) is my personal favorite. Her style of shoulder is comfortable for me and she has a lot of options on her website.
Jan's website: http://www.sleepingbaby.net/
SBP slings are really economical compared to many US ring sling makers. Jan offers a lot of fabric choices and colors, including wrap conversions (a ring sling made from woven wrap carriers)! She's easily reached through her Facebook page too. She makes slings as they're ordered, but they're usually made the next day and shipped out the day after that - amazingly fast turn around time IMO! She has a lot of help on her website for using ring slings and how to choose the right one for you. She even shares instructions on how to sew your own ring sling using her shoulder style. :)
I currently own a wrap conversion made from a BBSlen Pineapple wrap. It's a size medium. I wear a 4/6 in clothes and I'm 5'8", so you can see how long a medium wrap conversion sling is (the length is measured by the center of the wrap)! I had an issue with the long tail at first, but now I love it. I've used the tail to keep me warm on a windy day and it's a great cover for nursing. If it does get in the way, I just tie it in a knot or throw it over my shoulder.
These slings have a shoulder sewn as an overlapping knife pleat.
It's hard to see the shoulder well with my sling due to the strips. There are better pictures on her website!
Jan also sews an "Eesti" shoulder, which is very different. I haven't tried this shoulder personally.