Since you are only 16 your natural test levels are still really high. Almost all the responses you are going to get are going to tell you to stick to the essentials, such as protein,multi,fish oils, bcaas, creatine and the most important of all diet.
If your trying to gain weight at your age you shouldn't rely on supplements, in other words, eat eat eat. Starting a clean diet and hitting the weights hard will yield significant gains in the weight room.
As far as different companies go. Look at MST MVP/ZMK multi/mineral stack and Xtend for BCAAs.