The old version was great. I don't know about the new version because once I upgraded the old version it wasn't free anymore it keeps telling me that my one day premium trial is over and I need to upgrade to premium in order to use it. So youtube by click is no longer free.

I've tested 4K Video Downloader, YouTube By Click, KeepVid.com.

4K Video Downloader offers to choose from various resolutions and formats. Moreover, 4K Video Downloader allows to download video subtitles too (if video subtitles are available). I also prefer 4K Video Downloader user interface rather than YouTube By Click interface.

4K Video Downloader offers standalone installer that isn't bloated with addware (bloatware), contrary to YouTube By Click, which offers bloatware and you must be careful not to install that bloatware.

I've used to like KeepVid.com, but KeepVid.com doesn't offer downloading high resolution (1080p, 4K) for some videos. Also KeepVid.com was unable to download subtitles for some videos. In all of those cases, 4K Video Downloader worked just fine.

As of 2015-01 I'm going to use 4K Video Downloader as my primary YouTube downloader.
I recommend you try 4K Video Downloader first before trying other YouTube downloaders.