Don't buy a condo or a townhouse. They are almost impossible to sell when you want to leave. Rent one if you must. You can always find someone who can't sell his/hers and will rent it to you. Value often goes down, not up like detached single family homes with large lots.

You might consider buying a suburban house and renting it. Use the rent money to pay your rent on a condo or an urban apartment. If you are able to move there in the distant future, the value of the house will have gone up and you will not be stuck with a condo sell.