I totally agree with Shaz--depending on your body and stoma, what kind of bag that works best for you will be up to your own experimentation...!
I have used the Coloplast Assura Extended wear wafer, and I wear the opaque "midi" pouch with them. I like this pouch b/c it is so small; though I do have to empty it 2x each day at work (but it is so fast!). Ifigure when I had crohn's I was in the bathroom 10 times a day at work, so this is a great imporvement :).
I have had my ileo for about 5 months and not have one leak, not even a minor one, so this system has been great for me!! Good luck; I know you will find something you like a lot. IT took me trial and error for about a month.