I'd have the dark chocolate personally. It's listed on the P2 food list (as sparingly) and it does have a fair amount of antioxidant properties. For home use I stick to the NSA fudge pops for my frozen sweet treat fix. If I want ice cream, I go out and find the best quality I can, get a small size, pick a simple flavor (no added candy bar types!) and enjoy the heck out of it.

Ice cream was one of my huge nightly "medication" foods pre-SBD. No bowl needed, just sit down with a container and the spoon and eat mindlessly until I was done. So I'm reluctant to bring fake ice creams into the house and lull myself into thinking they can be used with any great frequency just because they are lower in fats and sugars. I'd rather eat the real stuff every so often and make it a real treat! The fact that I won't go alone, have to drive to get it, and it's expensive to eat it that way, all kind of self-limit the opportunities and it becomes what ice cream was meant to be, a social family event (think trip to the old fashioned soda fountain) that was a special treat. In the original book, Dr. A kind of says the same thing BTW, i.e. have the real stuff once in awhile (the high fat content actually mitigates the effects of some portion of the sugars GI-wise) and don't fool yourself into thinking the fake stuff is OK just because it's fat free and uses artificial sweeteners. Finally the ingredients lists on the ersatz stuff just squicks me out. Well so do the ingredients on the fudge pops to a certain extent, but I can rationalize it on those for some reason!
Anyway, that's my long answer to a simple question. If you can limit yourself to the half cup serving size on the diet ice cream and keep it to the occasional treat at home, it's probably fine too. I just knew that wasn't going to work for me. And frankly I like good ice cream far too much to settle for the fake stuff! It's kind of a no-compromises food group for me!
ETA: And we do keep several flavors of dark chocolate bars at home and have a few squares of it after dinner a few times a week. Esp. on nights we have red wine! Great taste combo!