I have stayed at all of these besides the InterCon. It really depends on your price range and what you're looking for.

The Emirates Palace is spectacular. It's worth a visit. I was there in August, which was great, because the rate was low and hotel was empty -- my travel companion and I had practically the whole beautiful pool and beach area to ourselves. In December, it will be more crowded, but, still, if you plan any recreation in the pool/beach, it's the best choice. Plus the rooms are gorgeous and the service is excellent. The amenities (e.g., food and beverage) are quite pricey, however, and the hotel is remotely located. Taxis are easy, but you can't really walk anywhere from there.

Le Royal Meridien is my second favorite hotel in Abu Dhabi, particularly if you can get the Royal (new) tower. A two-room suite that I had there was one of the finest hotel rooms I have ever stayed in. The restaurants and bars at the hotel are great, service is a step above any of the other hotels on your list, and it's centrally located downtown. The main disadvantage is that it has no beach, though you have access to the beach at Le Meridien (also a very nice hotel), but you have to go by car. Another minor disadvantage is that the club (if you are a platinum guest or are paying for it) is a bit disappointing -- it's in the lobby, and doesn't offer as much as the Sheraton, CP, or (I assume) IC.

The Sheraton (on the Corniche) is also very nice. It remindes me of Le Meridien -- great pool and beach, plenty of great restaurants, solid service, but a bit older. The rooms at the Sheraton are also strangely small.

The Crowne Plaza is OK, but nothing special. I would call it a decent functional business hotel -- also centrally located, with a handful of solid restaurants, a good club, and adequate service -- but nothing lavish. The rooms are a bit dumpy, although large. And be sure to stay below the 9th floor, because that's where the restaurants are, with an atrium above, which tends to smell of food.

The InterContinental, recently renovated, has gotten some good reviews here; you might want to do a search.

You might also look at the Beach Rotana, which is adjacent to the Abu Dhabi mall, and a step up from the Sheraton and Le Meridien. It's newer and pretty upscale. Also the Abu Dhabi Hilton (there are two other Hiltons in the city to avoid) is comparable to the Sheraton, but with a slightly better beach area.

If you give more specifics about what you are looking for, then perhaps I can give more specific advice.