Until a few years ago I used aida, but once tried the flax I can not help it, the embroideries are much more beautiful ... you just have to be careful to count :lol
I think aida is easiest, but some projects look better on a different fabric, so I use different kinds. The last project I did was on linen. I had a hard time getting the stitches even because the fabric threads were different widths.
I love cute tiny stuff, so evenweave and linen are perfect for me. Unfortunately I do not have enough money to buy them so... I use 18ct aida instead :D
It depends on the look I want, for an antique looking piece, I love linen. Mostly for other stuff I use Aida. As I get older, I have to use more magnification and it takes me longer.;P
For minis the linen is great.