Definitely Brasov. I mean, Bucharest would probably be more accessible, just having a direct flight and that's it, but Brasov is so much more worth seeing. Plus, Bucharest will get you horrified. I mean, it does this to us everyday, and we've been living here for our whole lives.
So I'd suggest you should take a Bucharest-Brasov train after arriving and you're gonna be there in like 3 hours-max 3 hours and a half. Accommodation is also easier to find, Brasov is a much smaller city, safer and faster to get from one place to another aaaaand it's a pretty town too. Like, mountains and stuff.
Hope everything goes well with your journey, there's still plenty of time to plan stuff till march. If you ever have any other question, I'd be glad to help, just PM me or something.