I use Bandicam for all my recordings. Bandicam usually compresses reasonably well but I also usually run the files through HandBrake with custom settings for YouTube afterwards to get the file size even smaller.
I chose Bandicam over Fraps because of the compression; the ability to record the screen as well as applications; and that it didn't impact my FPS too much.
While recording DayZ I did run into some problems with recording so I wound back my version and haven't had the issue since.
A half hour recording at 720P, 25fps is usually about 3 to 4 Gb. Once they are processed through HandBrake the files are usually between 600 and 700 Mb. To put this in perspective, the files recorded from Bandicam are about 10% the size from Fraps. The Handbrake processed files are about 2% the size of the Fraps files.
I've used Bandicam for over a year now and love it.