To be honest TC, just pick one and play. If it's too hard, turn it down. If it's too easy, turn it up. The only difficulty related achievement is playing on Insanity, so it doesn't cost you anything to change it.
I don't really remember how the difficulty compared to ME2 when I first played, or even which difficulty my first playthrough was on. I do know that, after playing MP on gold, I can't play the SP on anything less than Hardcore. It's easy to the point of being boring. And for me, that's saying something, because I'm definitely not the type of person that plays the highest difficulties because I enjoy it. Most games I never play beyond normal, or whatever its equivalent is. --- There are 10 types of people in the world. Those that know binary, and those that don't. GT:Talon Omega. If you send an FR please tell me where you got my GT.