V6 will easy the plugin writers so we can see practical plugins in due time like the Altium to KiCad (not the external conversion program). They are processionals and they know what they are doing. The KiCAD team will go to a year release circle which is a fantastic decision. I am working with the nightly builds since KICAD5 released. KiCAD is getting better and better every year and that is a fact. I had a few issues with some vias, but it was easy enough to fix. I have used it before and gotten acceptable results. There is also a format converter for kicad that allows you to import Altium designs into KiCad. I also have not looked into it that much but one of the focus areas for KiCad 6 is the netclass rules system, so it should be pretty close to feature parity by then. Its not much of an issue for embedded systems. The net class rules system in Altium allows you to more easily set clearance rules between different nets and is useful for things like power electronics, when you have a set of nets that can gave traces close to each other but far away from the ground plane. KiCad keeps improving, but with KiCad 5 the biggest disparities between KiCad and Altium is the ability to check 3d component clearances with an enclosure in real time and the net class rules system. KiCad also seems to have a lot less perplexing errors. I find the KiCad interface a lot more responsive and find the UI more intuitive. I have done work commercially in both Altium and KiCad and use KiCad for personal projects.

Altium kicad importer