Some are markedly better than others. And some are more in demand because their AT is more heavily played. Just based on my experience buying and selling them in the AH, I'd tier them as (alphabetically within tier):
Top Tier: Blaster, Brute, Tanker. These are consistently in demand, and have nice bonuses to boot.
Middle Tier: Controller, Corruptor, Mastermind (Mark of Supremacy), Scrapper, Stalker. Sometimes there is a demand for these, sometimes not. The bonuses are generally good, but supply quickly knocks the price down.
Bottom Tier: Defender, Dominator, Kheldian, Mastermind (Command of the Mastermind), Soldiers of Arachnos. Either sub-par bonuses or lack of demand for AT. When I get these I usually convert them to a higher tier.