What is a good screen recorder?

What's a good screen recorder that will record a specific window(NO$GBA) that won't make sound lag behind.

Hmmm, I would say Camstudio

This could probably get added to the sticky, but in my experience these screen recordings softwares are now getting blatantly beaten by streaming software that allows you to record locally. There are two programs I use and they are way more functional and include way more features then programs like CamStudio.

One would be xSplit, if you have a job or some money to spare, this program gives you the ability to record locally at any size (if you buy the license) with any mixture of sound and microphone. It also allows you to layer and move video sources inside the program so you can have various things like a webcam, image overlays etc which saves some effort if you don't have a post editing program. You also have a vast amount of options including recording frame rate, video quality and codec as well as audio quality and whether you want the audio seperated.

The free option would be a program called OBS (Open Broadcaster Software). This has all the options of xSplit and more. It's interface is much more complex and not so user friendly but it has all the same functionality as xSplit. The reason I use this over xSplit most of the time is that it is much less CPU intensive and developers are working to create plug-ins and better functionality all the time. A HUGE advantage this has over xSplit is Microphone Noise Gate. This allows you to test to see how much noise is coming through your mic and to actually mute a majority of it. If you have a decent mic you can get virtually crystal clear audio. If you're mic isn't as great you can still block off most of the noise while leaving a little so that it still captures the softer sounds in the voice (you'll get jitter and mic cut off if you block too much noise for sounds such as r, e, etc.

I'd recommend any let's player to check those programs out.

tl;dr

Got cash and need user friendly features - xSplit

Not afraid to spend a little bit of time learning about the technical specifics - OBS.

I am an endorser of using OBS pretty much. You'll need to sit down with it, but oh jeez it's worth it.

I think this has been answered fairly comprehensibly, so going to close. I'll point out that questions like this are better suited for the thread sticky here too, for future reference.