I am going to make one recommendation, and only one:
Don't get one that looks exactly like a cigarette (i.e. white battery, orangish-beige atomizer/cartridge or cartomizer, red tip). Get one that has a blue LED tip or another color, and one which doesn't have standard cigarette coloring to it.
In the first week of experimentation, I used one which was cigarette-identical in design, and not only was I constantly accosted by people asking me for a cigarette or a lighter, but I had people nagging me incessantly to not smoke around them because they had to breathe the secondhand smoke, and they didn't care that it wasn't actually smoke.
If it looks like a duck and acts like a duck, the rationale goes, it's a duck. You'll get more flack for a cigarette-sized mini that looks like a cigarette than you will for something that's, say, black with a blue tip. Or white with a green tip. Etc, etc.
I could make other recommendations based on experience, but I've come to learn that people need to do their own trial and error. The fact that my own Joye 510 kit is sitting here gathering dust when I'm using my ego/Riva isn't important, either. You need to play around with what will work for you, and I respect that... and there ARE people who are more comfortable with a cigarette-sized model.
But if you want to avoid people who smell like cigarette walking up to you all the time and asking for cigarettes... go with something subtly different. That's all I'm sayin'.
