If you intend to work in the field, KiCAD has very little penetration as of this moment. It’s better than nothing, but mot companies will prefer people with experience in Altium.

If you just want to start doing some projects, KiCAD is mature enough and you’ll find more tutorials and content.

I use Altium Designer almost exclusively now (Was OrCAD/PADS previously)......if I were starting over, I'd get much more into KiCAD. Higher learning curve but you can get legitimate professional-grade PCBs designed in it.

The long-term answer is that you'll eventually want to try all of them. In my opinion, half of PCB layout is tool-agnostic and the other half is getting fast/proficient at a specific tool.

When I moved to Altium, I knew that I wanted to "pour copper" to make a power plane, so I just had to google what the Altium equivalent was. The PCB concepts of layers/routing/grounding/clearance/vias/stackups and all that are universal, the terminology and shortcuts are just changed between tools.

I absolutely love Diptrace. It has a free version with all libraries included. Over the years though I have progressively upgraded it to the "standard" level (which allows 6 layers and 1000 nodes) when they have sales. My own microcontroller designs with GPS and bluetooth, OLED displays, serial ports etc. have not passed 500 nodes.

Definitely KiCad unless you need really high-end features immediately.