It's all about who you are and where you think you'd fit in. I don't want to say too much because I'm clearly biased but will try my best to remove that.
Remington, Charles Village, Hampden, Waverly are a little more "hipster". Remington seems to be going the way of the yuppy right now though. More creatives/students live there. They are all clustered off of 83 north of downtown but below the rich Roland Park area. You will find that "the avenue" in Hampden is full of eccentric coffee shops/restaurants/shopping.
Canton and locust point are more main stream young professional type areas. There is a lot going on there. You won't have to look hard for kickball or ultimate frisbee or dog parks or restaurants/pubs/grocery stores. More professionals live there.
Avoid living downtown (just my opinon - lived there though). It's Mt.Vernon which is overpriced and over rated.
I've always seen the typical Baltimore progression as
Graduate college
Move to Federal Hill to hookup/party like it's still college
Move to Canton because it's more serious/less trashy down there
Get married and move to the suburbs because we can't send our kids to these schools, are you crazy!?
before anyone gets too butthurt there are plenty of exceptions. you're very special, we know.