I personally don’t care about the weather, i live where it’s cold in the winter and hot in the summer, germany in fall or italy or france or denmark are all good.
I personally would like to spend more time in germany, we could do Berlin or another place beside munich during oktoberfest and possibly get a good deal on rooms. I love the beer in Dusseldorf, i’m sure i’ll love it in Berlin too.
Bigger cities are easier, cheaper to get to.