Two recent rappers that I can recall doing it well off-the-top and somewhat often are ASAP Rocky & Charles Hamilton. It's tough though because 1) we're in the age where every thing is recorded and used to slander you and 2) there's nothing to be gained (respect-wise or monetarily) these days from being able to freestyle off the top. Charles Hamilton would freestyle off the top for LONG stretches of time. It was cool, but nobody REALLY cared. 
People judge the hottest emcee based on their music. You just put the hot verses on your features/mixtapes and get just as much credit these days.

People judge the hottest emcee based on their music. You just put the hot verses on your features/mixtapes and get just as much credit these days.



and will compare shyt off the top to pre writtens and be like like "damn so and so sucks at freestyling" lol