Basically when Tekkit was first made, they used almost every single mod out of 30?+ mods in the pack without permission. This lead to a lot of modders fighting them, because they were using their mods, illegally, and were allowing people to donate to them without having a link to the real modders donation pages. (So they were basically using what other people had made to make money.) Now, they still use 5 or 6 mods without permission, and they still make money off of it by allowing people to donate but don't have a link to the real modders donation pages. What's worse, many noobs that use Tekkit think Tekkit is just one mod. They think that the makers of the pack made all of these mods and think the real makers of the mods just copied Tekkit. So it is probably the worst pack ever made. FTB however, was made by modders like Pahimar, SirSengir, Eloraam, etc. so they have permission from all of the mods that they use. And they update more than Tekkit, have more packs, and have a community driven wiki. FTB FTW.