CANON 90D vs CANON R10

amos roth wrote:

From the discussion I understand that nobody recommends to replace an old 600D with a newer DSLR (the 90D is the candidate), and most people would prefer to switch to mirrorless, even if using the existing lenses (all EF or EF-S).

I understand the disadvantage of using EF-S lens on mirrorless camera are minor,

but I still have doubts about the ergonomic of the R10. I feel better to hold the 90D (specially during tracks, even it's heavier), than holding the light-weight R10. The 90D feels more robust, at least for me.

At the bottom line - I'm more confused now than I was yesterday....

Photography is all about compromises and the pressure you feel is that there is no one right answer to the question you have posed.
The premise of most of the answers here  (and I think your question) is that you want to upgrade your camera body but keep your existing lenses.  That obviously helps the budget immensely.   But I think long term, those EFS lenses may be the tail wagging the dog, by which I mean they are limiting your choices to only two cameras: 90D and R10.  I think the question you might need to ask is,  will those lenses move you “to the next level?  One of the generally recognized weaknesses of Canon’s crop sensor cameras is the poor selection of wide angle lenses.  For your landscape photography, do you use a wide angle lens? It is entirely possible you don’t but is that a current or future need? If so, neither the EF-S nor the RF lines have really strong offerings (though the EF-M line does). Maybe a long term plan to transition to Canon Full Frame or some other brand entirely would be the right step.