I've taken BCAAs in powder form and in pill form. Since I realized that I wanted to try and take them intra-workout, I decided to get some BCAA powder. The first time, I got the unflavored stuff. I'm not really a picky person, and can stand taking some gross-tasting stuff if it's for my health. But .. oh my gods. I couldn't handle it and ended up capsuling them myself. This time around, I caved in and got ModernBCAAs with flavoring. It doesn't have phenylalanine in it, but it does have sucralose, which I am okay with on occasion. It also has the least amount of added ingredients that any other of the flavored BCAAs had in the whole store.
As far as appetite suppression goes, it works okay for me. BCAAs give me a little energy, help with muscle soreness due to weight lifting, and allows me to wait just a little bit longer between meals if I want to. Sometimes, I'll drink some before bed, just because I often wake up in the middle of the night from hunger, and I've found taking BCAAs help me to stay asleep.