Ooh most of my new and old hg's are mentioned here! Ok well, I love all these mascaras (in their waterproof versions though, my lashes ONLY hold with waterproof) and here are my 2 cents.
L'Oreal Voluminous: Agree with Kels, for thicker and more dramatic lashes, this one's probably the way to go, but an eyelash comb pretty much necessary or else you'll get some clumps. Also, it's one of the darkest 'black' drugstore mascaras I've used.
Maybelline Full n Soft: Still agree with Kels, it's not as dramatic as Voluminous off the bat, but I love the fact that it's buildable, so to me it's pretty versatile. One or two coats for a soft, defined look or more for thicker longer lashes. I find this lengthens the lashes better than voluminous, too.
As for Max Factor 2000 Calorie, it's my current HG along with Max Factor Volume Couture. For me, 2000 Calorie is like Voluminous but perfected. A better brush, just as much thickness as well as definition, and it's pretty dark too. It flakes less than Voluminous and Full n Soft.
All of these are great mascaras! Choose based on the look your after. Personally, I think they're all worth owning
edit to add: Hm, my Full n Soft tube is all dried up *tear* but I can do comparison photos of Voluminous, 2000 Calorie and Volume Couture if you like. Let me know