If you have a nVidia GTX 6 or 7 Series card I'd highly suggest nVidia Shadowplay through nVidia GeForce experience, it allows you to record your gameplay AND your voice with no loss to performance, the only downfall is that it cannot yet record Open GL 2.0 games (Like Minecraft) but can record everything else like BF4 etc..
Fraps is also decent but there is quite a large performance drop when you record which makes it very annoying.
Another alternative which I haven't tried personally but people say is good, is dxtory, although I haven't used this so I don't have much to say about it.