I consider all non starchy vegetables pretty much "magic"- a universe of variety and incredible nutrition for a handful of calories. Nobody gets fat from eating too many carrots- they just turn yellow
I can't say that there is anything that "doesn't matter"...everything is a choice and every choice has it's impact. That said, if you're looking for things that are less likely to mess up your plans:
Raw cauliflower/broccoli are fantastic for you, packed with all sorts of good things, and require lots of chewing.
Also, air-popped popcorn can be a good snacky food...
There is no magic food, but there is something that increases your energy, decreases cravings, improves your overall fitness, helps dispel a bad mood, and boosts your metabolism. It only takes about half an hour to prepare, but you need to be a part of the process the whole time.
It's a walk, and every day I kick myself for looking for a "magic bullet" for improved health, yet never got off my *** and took advantage of one of the best ways people have of being healthier.
Aside from walking to keep cravings at bay, most non-starchy vegetables are pretty low-impact, calorically speaking. Leafy greens are good for taking up space. Air-popped popcorn's also a good choice.