I use the Korg. Digital is good because you can be precise. A metronome is a useful practice device for many reasons. If you're in a band, like I am, sometimes by agreeing on a metronome setting for a particular song, each band member can practice on their own and be on the same page with the other band members. I only use the metronome when I'm practicing on my own. We never use it when the band is playing together.
Also, sometimes it's possible that you think you are playing the rhythm well when in fact, you're not. The metronome will tell you whether you're on or not. It can be helpful too when you want to start bringing a song up to performance tempo. You can gradually increase the speed.
At some point though, it is important to turn the metronome off and start trusting your own tempo. So, I would say, you need to find a balance between using this tool and not using it. It depends on the song, and on your own style of learning.