Well, I worked with altium and kicad for almost 8 years. There are more subtle differences than the autorouter, and this is basically a trivial thing because I rarely use it. For example, kicad does not have some advanced features like via fencing, via picking, lenght matching, and some more. Is true that you could download a third party plugin, but is not the same.

Variants are the same, you cannot do it in kicad and altium is a breeze. It give you the flexibility to build different versión of the board in seconds.

Also, the library management is, in my opinion, very error prone. I get the flexibility and I find it useful in some cases but...

And the last is the design rules UI/UX is very simplistic, and you need to know what you are doing. Which is not bad per se, but for a software oriented to mainly begginers, I think is a bad idea. Besides you cannot import/export rules from one project to another and this is a killer for me.

I hope some day kicad will be a solid competitor to altium but right now I cannot fully do all my work in kicad as a electronics engineer, so even Altium is expensive, is a much needed tool.

Edit: I stand corrected, kicad indeed has lenght matching.