I'm 5'10" and a friend of mine is 6'2"...two years ago we ordered our WM Badger bags at the same time. I ordered a regular and he ordered a long. When they arrived, I picked up both bags for us and brought them to my house because my friend lives out of town. When I got home I climbed into my bag, and it was a perfect fit right out of the box...not too big, not too small for the past two years and still going strong. That said, if I were much taller, I think I might be pushing the limit in length and bordering on compressing the down at the foot of the bag at times. I was initially wondering what a long would have been like, so I climbed into my friend's bag when I first brought them home, and it was way too long for me...but at 6'2" it is just right for him and he is very comfortable in it.
That's my qualified way of saying as a 5"10" guy to a 6'1" guy...consider getting the long...even though it might feel a bit longer than you need and wondering if a regular would have worked for you.