I lived in Bucharest for a bit and settled in Cluj-Napoca at age 33 (single at the time). I chose Romania over some other countries in the region because of English speaking proficiency, and Romanian is easier than some of the Slavic ones.

Bucharest was fine. The lack of decor started to wear on me after a while. Cool thing about Romania is that you can rent pretty easily and leave with one month's notice even if you signed a one year lease. A decent 400 SQ ft studio in Bucharest or Cluj (the most expensive cities) won't be more than $350 a month.

Definitely worth considering too. Bratislava is really close to Vienna, probably more West European in culture than others because of physical proximity and history.

I'd explore all these, may be do a few months stay in each city, that would be really cool experience you could tell stories about.

Btw if you go further east check out Chernivtsi, it’s a hidden gem in the East Carpathian mountains.

I lived in Belgrade for a few months with a Serbian friend. Absolutely loved the city and the people. Found it to be incredibly affordable with a great night life, especially if you're in your 20s and want to meet university girls.

Language wise, most people under 30 had some basic English, I spoke almost no Serbian at all but still managed to get by at stores and restaurants. Internet is cheap and widely available.