Exotic new supplements, including BCAAs, extracts from fancy sounding stuff:
-It's probably a scam. Shit like green coffee bean extract, whatever, it's essential oils for bros, marketed to you by people on steroids. T boosters are probably bullshit if they're herbal or whatever. Your best bet for elevating t levels naturally is building muscle and losing fat, sleeping regularly and keeping your head on an even keel as far as stress goes.
-Casein is a longer-lasting, slower-digesting protein with a worse profile for solubility and drinkability. It's the primary protein in cheese and it tends to clump up and get thick. I haven't bought it since I'm satisfied with whey, but I've heard bad things about thickness and drinkability. Some people prefer it, especially as a before-bed protein drink. If you really want casein, 250g or so of cottage cheese will give you a big dose of casein and whey and it tastes fuckin delicious. Maybe the economics work out differently for you.