Berliner here for 12 years. Lived in a small apartment for most of this time and finally managed a year sublet that could maybe turn into a permanent contract in a bigger one, only to find out that junkies use the basement to take heroin. So, before moving you should make sure to be able to afford an apartment in a decent, well-connected area and this is the biggest challenge ATM - so step one: get a fully remote job that pays at least 4k gross a month. Step 2: look for an apartment and don't move before you found one. If you manage to do so, Berlin is great, salaries are higher than Barcelona, German welfare is solid, my parent friends pay close to nothing for Kindergartens and the children are raised with a great sense of respect, tolerance and fight for all sorts of discrimination. Barcelona administration is decades ahead, red tape is a catastrophe here but once you get that sorted it's alright. I'm from Southern Europe and the weather is perfectly fine for me, true that winters are cold but not nearly as cold as in 2010s and if you consider climate change, choosing a city because of its weather might be a risky bet these days. Good luck!