Over the past three weeks, I've had the opportunity to stay (not by choice) in all four of the full service JC hotels. Here's my take on how they rate:
1. Hyatt Jersey City. It's not even close. The Hyatt is by far the nicest destination in JC. This is truly a lovely hotel, and would be a pleasure to stay at in any city. Public spaces are incredibly sleek and handsome - the lobby and restaurant, which overlook downtown Manhattan, are just gorgeous. Rooms are also very nice, with excellent fixtures throughout, and the whole feel is upscale and modern. The beds are wonderful, and each room has that incredible view. Everything works. However, these are also the smallest rooms you'll find of the four JC hotels, so if you're in it for space, there are better alternatives. Also, this will generally be the most expensive hotel of the four, but, surprisingly, it isn't always, so it's worth checking out.
2. DoubleTree Club Suites Jersey City. Second place was honestly a toss up between the DT and the Courtyard by Marriott, but the DT gets the edge because a) all of its rooms are mini-suites, and therefore offer more space, and b) it has a "real" and handsome restaurant, a place you wouldn't mind eating. Outside of the size, the rooms here are pretty standard - nice enough, clean, and all come equipped with a fridge, small kitchen sink, and separate sitting area. The layout of the rooms is a little awkward (trying to see the TV from the desk space is a bit of a task), but it's not a big deal. Rooms facing south get a bit of a Manhattan view, too. Beds are very nice here. Outside of the restaurant, the public spaces are pretty basic. Overall, there's no luxury feel here, but it's clean, functional and spacious - and the convenience of a restaurant and room service helps. In terms of expense, it usually is priced just about the same as the Courtyard.
3. Courtyard by Marriott Jersey City. As noted, this could have tied for 2nd with the DoubleTree, if not for the plastic cookie cutter restaurant and the fact that most rooms aren't suites. However, this is one of the nicer Courtyards I've stayed in. There's a very limited range of how nice these can be, and like all of them, the rooms were good sized (couch/sitting area is a nice touch), beds were standard, and everything was very clean and generic. But the public spaces were a little nicer than the standard Courtyard, with an outdoor sitting area in the back of the hotel, and a cozy lobby area. I also prefer this location to the DT, as it's in the middle of some good restaurants steps away, and is adjacent to the PATH subway train to Manhattan. Also, maybe 1/5 of the rooms have Jersey City's only hotel balconies, and if you can get one of those rooms, it's a nice feature. In terms of price, as noted above, it's normally tied to the DoubleTree's price, so you don't often see a difference between the two.
4. Candlewood Suites Jersey City. Normally the cheapest of JC's hotels, this is also the least-nice of the four. Everything here is totally generic and plastic. That said, it's similar to the others in that it's clean, spacious, and comfortable enough. The junior suite I stayed in was really like a small studio, offering less space than the DoubleTree's suites, and probably less space even than the Courtyard's standard rooms. Full suites, I imagine, are bigger than the junior I occupied. What's nicest about this place is the fact that there's an actual kitchen area, where you can cook, have a pot or two, plates, silverware, etc. So, it's nice for a family stay. The parking is also free here. The location is the most awkward of the four, sort of in the middle of some warehouses and office buildings, but not far from anything the other hotels are near.
Hope this is helpful.