It all depends on what your looking to record, If your looking to record game play look into Fraps, I recently picked up a copy and it has done well for me recording DayZ/Minecraft/black ops 2
I use the "paid" version of Camtasia Studio. I like it personally because you can edit all your videos, render them into HD, upload directly to youtube. Obviously a program like this isn't free so you can always get the cr4ck3d version of it from thepir4tebay. hehe ^.^