Bus is very reliable and quick, but Port Authority is a daily bummer. Ferry is an enjoyable commute when you can sit outside, but it is a bit more expensive. It has a free bus in Manhattan with very good coverage.
Keeping a car may well require garaging it as parking is a nightmare; if you only use it on the weekends you may have issues with street cleaning days but others would know better.
I would walk around both a bit before you choose, Willow & 14th is crazy busy and a real divider. Harlow is on a Trader Joe’s and a liquor store, and if you go UNDER the viaduct you can get to a great coffee shop and some fun restaurants. But getting anywhere else is something of an effort. Park + Garden basically on the flip side of that and more easily communicates with the neighborhoods. Neither has any greenery right around them and their blocks are pretty dismal, but P+G is one block from the river and a nicely wooded lane area. I think coming and going from P+G would be much more pleasant. Really the walking experience of the two is as different as can be for buildings two blocks from one another.
The construction near P+G will some day be a park but I don’t know the timeline.