The bottom line for Agents and Associate Brokers is that we are not allowed to give any opinions as to the "safety" of a neighborhood or to discuss one neighborhood as "better" than another. Alex should be careful as his remarks could be considered discriminatory or an attempt at steering. Both are illegal.
The best way to "check out" any neighborhood is to go there at various times to see neighborhood activity. You should also check other things that would allow you to make an informed decision. Transportation, shopping, green space, schools, medical/hospitals, and more would IMO, be additional criteria in any decision to purchase based on need. Good luck with your decision.
All of Harlem has great investment opportunities. The large majority of Harlem is safe!! Morningside Heights and South West Harlem are very very nice neighborhoods. East Harlem has greater investment potential (lower prices) but higher risks in my opinion. Simply because they have large amount of public housing which sometimes is an indicator of "problems". However there are plenty of great residents in public housing as well it's just the risk is greater.
In my opinion the best parts of Harlem at the moment are South Central Harlem (from 5th Ave to Manhattan Ave below 125th St) & Hamilton Heights 135th St to 155th St along Broadway.
I live in Hamilton Heights and love it!! Riverside Park, Diversity, Trains, restaurants, all very close. Think Upper West side without the shine. If you want more information and/or help please let me know I would love to help you in your real estate venture. I am a life long New Yorker and have been exposed to Harlem since the 80's so I can give you a real assessment of the neighborhood. I hope this was helpful.
250 Park Avenue South
New York, NY 10003
Transportation on the west side is much better you have the A, C, B, D. and the 1,2,3 train lines.
plus many bus lines.
On the East side you have the lexington Ave. lines 4,5,and 6. plus many bus lines. Several bus lines have limited stops. In 2016 the 2nd Ave. train should open starting from 96th - 59th streets.
I hope this helps you in your decision making.