I just did a kicad quick code review yesterday. Just to see what it looked like.
https://www.eevblog.com/forum/eda/kicad-code-review-after-a-quick-poke-around-in-the-source/I am very happy to use Kicad, I tried to start on Eagle a couple of times but stopped, I was probably a bit prejudiced against it because it looked like a Win98 UI.
I am currently using Kicad professionally, I am not sure if that means much.
Probably the only problems I have with Kicad are
1. I end up having to create a lot of my own components for the library both schematic and pcb because the Kicad libs are not as comprehensive as Eagle, but it doesn't take long.
2. The changing the track widths and spacings and its integration with DRC I find annoying. The main problem stems from having a net that has two settings. I am not sure the best way to manage this. eg. Make a track small to go into a 0.5mm pitch pin but then widen out if it has to go a long way. I end up having to defeat the DRC to get around this.
The issue with via stiching is really a non issue. You have to identify a via as part of a particular net anyway, the easiest way to do this is to join a dummy track to it. I don't know how they do it in Altium, but it is really not a problem in Kicad and so I doubt they will change it.
One piece of advice I would give to you no matter what EDA you choose is to put Source control (such as SVN) onto your library files and your projects. It will save you a lot of grief.