If you are afraid of hotlinking just add some code to your htaccess to prevent any views of images from external sites.   If that will work i can show you how.. 

You can also use watermarks and there is a plugin for that as well. 

On mikes plugin our leader darryl got it last year i guess and rates it high, i know darryl well, if he says its great then its great.  He is on vacation for a few more days, he might actually even be back tomorrow.  You should send him a PM and ask him about it before you buy it. 

here is his link  https://developers.oxwall.com/user/dgbeard

Skalfa is also good so i guess look and see what features you really want.  But again i would talk to darryl first. 

Mike's was the first one in the store. It is a standalone plugin. The private albums are shown on the profile page. The privacy settings include friends plugin integration, password, public, and selected users. It has worked well for me. I haven't tried the other plugin, so I can't really say to not use it. I know it is integrated with the system, and private pics are displayed in the photo list page, but with a padlock.