Acrylics vs. Enamels on glass
I own a lot of specialty paints including enamels for painting on glass, tile, etc. I don't particularly find it hard to paint with acrylics on glass, I just don't like the prep and finishing you have to do to keep it on. With enamels you just clean your surface, paint, let cure, and you're done AND they are permanent...another reason I like using enamels. Over the last several years I have come to like paints made for specific surfaces, it's just easier.
But I do like sponging acrylics on glass to create a country crock-like surface for jar candles and have used the same technique on my lightbulb ornaments. I've shared these before but the following pics are of a mustard jar/terra cotta pot candle done in acrylics and a wine light done with enamels. The one thing you have to remember about enamels is that they will dry with a glossy appearance. A lot of times it's all about the finished look you are trying to achieve.