I currently have two ankle holsters for my S&W J-frames:
an Uncle Mike's inexpensive nylon
http://unclemikes.com/products/holsters/concealed-carry-holsters/ankle-holsters
It works very well for a lightweight revolver. I haven't had a need to use a calf-strap with this combination.
The other ankle holster I'll alternatively use is the Galco "Ankle Glove".
https://www.galcogunleather.com/ankle-glove-ankle-holster-_8_6_1019.html
I saved some money by finding a lightly used one on Ebay. The version I wanted had no thumbstrap. I did end up spending even more money on it, however. When I wear it around a duty boot, I needed to buy an optional extender as the standard diameter was too small. The holster works fine without the extender if just going around my ankle w/sock.
A holster which didn't work well for me was the Fobus:
http://fobusholster.com/Products-and-Accessories/Ankle/?1=
Fobus has made some changes over the years, but I've not tried it again. The problem was (and perhaps still is a problem) the velcro-type strap was just too thin of a material. The strap would bunch-up in its buckle. Although similar to the Uncle Mike's in function, the strap was unsatisfactory to me.
Another holster I can only give an honorable mention is the DeSantis "Apache" holster:
http://www.desantisholster.com/APACHE-ANKLE-RIG
I don't have one for a revolver but have used this holster for a Glock 43. I did have to put some moleskin material on the thumb-snap as it can rub into my calf right through the skin.
With all ankle holsters, I've found it important to find just the right spot to avoid the ankle bone and not rubbing on my calf. There are other brands out there but I've just never gotten around to buying and using them.