Hoboken is beyond a doubt the best place for a young single person in the area. I lived in both Jersey City and Hoboken when I was single. Jersey City is nice but only in certain areas, mostly near the river. The pro's are its proximity to the city, easy access via the path train or ferry and the nice new high rises with incredible views and amenities. Cons would be if you walk two blocks in the wrong direction it's a VERY BAD neighborhood. also I thought it was a little quiet as far as nightlife. I found myself taking the monorail to Hoboken for nightlife and dating. Hoboken has endless amounts of great restaurants and bars all within walking distance, easy access to the city via the path train or ferry and so many young people you feel like you're on a college campus. Mostly young professionals commuting to the city and single Airline pilots trying to relive their youth. The cons are it's pricy for something nice. If I remember correctly almost 10 years ago I was spending $2500 a month for a 1 bedroom apartment. I had an elevator, parking, and a water view, which brings me to the next con which is parking. I have never been to a more difficult place to find parking. If he moves to Hoboken make sure he has parking or gets into a parking garage, which can be a few hundred a month. Just make sure he does his research, there are some wonderful places to live in the area and many not so wonderful. Good luck.
Dave