The Aeris, Sherwood and Oceanic are all pretty much the same thing with different cosmetics. They are all made by the same company, Pelagic Instruments. Go to their respective websites, download the manuals and compare. The Cobra is distinctly different. It will give shorter no-stop times on repettive dives. It is also nice and small. I can't say that there is a right answer to your question. When combined, the various Pelagic computers are the most popular in North America and the Caribbean. In the rest of the world it is Suunto. Popularity does not matter per se, but there is no available information showing divers are getting bent more often because of their brand of computer. You will find users of all of these who love them, and a few that hate them.
Personally, I use a wrist mount Aladin and a separate SPG. That combination costs less than an AI computer, by the way.