Sharif, what amenities do you require ie, close to bus. close to water, affordablility,close to city... there are many area's in the bronx which offers condo's but it depends on your preference of amenities that i mentioned above. you may email me some of your preference and i can advise you on the areas that will fit your needs.
I've included a link below that may answer many of your questions. My opinion is that Riverdale and near Fordham University - Bronx campus - would be promising locations to purchase. Are you looking to purchase for investment or to live?
If you have the opportunity, you should walk/drive around the Bronx to determine where you would like to purchase. There are so many variables to take into account when purchasing that I recommend you speak with a Realtor to help you determine what neighborhoods meet your goals and budget. Feel free to contact me or Adina Greenberg. Adina also posts answers on Trulia and lives in Riverdale-south Bronx.