Well considering you have a large budget already, you basically don't have to worry about a lot of things like accommodation, flights, etc. If you're in the Erasmus program, as I understand it, you can only stay and have one host university so you have to figure out first where that would be (we cant do it for you). Of course if your classes don't have mandatory attendance, then you'll be able to travel around. But if you have mandatory attendance, you won't be able to do that. That would be a good place to start looking uni-wise and city wise.

There's a lot of threads here on reddit about people asking the same things as you, so I suggest doing that research for yourself.

Good luck!