AiMesh with AC3100 and AC2900, which should be the router and which should be the node?

[Queueball]

I have a GT-AXE11000 and I'm using my old AC3100 as a wired node. I read it is not recommended to mix AC and AX routers in an AiMesh system so I was going to donate my old router to my neighbor that has an AC2900 and get myself a different AX router for my network. My question is; which should be the main router and which should be the node between the AC3100 and the AC2900? They are very similar on paper other than the slight transfer speed difference and the faster processor in the AC2900. Is there something I'm missing that makes this an easy decision that I am either missing or don't know about?

 

[L&LD]

The RT-AC86U is superior as a router vs. the otherwise also excellent RT-AC3100. The 'AC3100 should be the node.