I always pick snaps over aplix.
I have had a love affair with side-snapping for some time now, but lately front-snapping are fitting DD so well. I think it depends what sort of fit you like. I prefer more of a "bikini fit" to deal with those chubby baby tummies, and I'm finding the FS do that better. Still, I'm getting a mixture of both styles for my newborn/small stash. If I like the diaper, it's not a huge issue to me whether it is front or side.
Fabric: Well, I love the feel of sherpa, but cotton isn't all that absorbant, and many layers of sherpa can be quite thick.
For absorbancy, I love hemp fleece (smooth side out - I just cannot get the fleecy part to stay soft after washing) or just regular hemp/cotton. Once I solved my "stinky hemp" issues, hemp returned to be my fave fabric. However, I did order most of my nb dipes in sherpa b/c I am assuming absorbancy isn't quite so important at that stage, and sherpa is so soft and yummy!
I don't currently have any velour diapers, but the velour wipes I have aren't so soft that I'd want a velour inner. But I ordered some of my nb fitted with velour outers b/c they are very pretty!!
I don't like flannel. All I have pills and gets a bit hard after a while, and it's really not at all absorbant enough for a whole diaper (IMHO). I have a couple dipes with flannel inners, just for the cuteness factor, but mostly I avoid flannel.
Cotton knits versus wovens: these are usually outer print materials. Knits are softer and stretchier, wovens are more like bedsheet material. but some wovens come in such lovely patterns!! I imagine without the stretch factor, you wouldn't want these on a one-size diaper, or one that is meant to last through many sizes, but I have some for my nb diapers b/c the patterns are so pretty.
I could take or leave micro inners. My DD really doesn't seem to mind wetness against her skin (for a reasonable amount of time). Covers with micro can be nice for extra protection, but also can be easily soiled (with plain PUL you can just rinse poopies under the sink, hang to dry, and easily reused that way).
I agree with whoever said always get a doubler. Only my nb diapers don't come with them, but I have a few extras lying around I can use if I want. Any other diaper I get a good doubler. When comparing prices, be sure to take into account whether doublers are included, what fabric and how many layers they are.