Trading up is possible. My local uni is ranked in the 500s, my new one is ranked in the top 50, and top 15-10 in my fields of interest.
The rates of many schools make it a gamble. For some, only a couple of spots go to hundreds of applicants. A lot of it is really is luck. You can apply to those schools if you want, but have some “matches/backups” as well. For me, staying at my local uni wasn’t an option, so I decided to focus my time, energy, and money on schools with better transfer rates.
“Given the difficulties and ordeals of transferring (leaving your friends behind, readjusting…) which schools would be good enough to make up for it?”
You’re using your own metric and there’s nothing wrong with that. The choice is ultimately yours. My criteria wasn’t as rigid, I guess. For me, it just had to be a school in the top 100 (match/backup) and top 50 (ideal) on most rankings lists, plentiful in resources in my intended majors, and able to sufficiently prepare me for a top grad program. I had a long list that was narrowed down by time constraints, and for some schools, a lack of a compelling reason to want to go there besides “it’s prestigious.” (That’s not really enough to work.)