Wassup Brah, I've tried all 3. Here's my take on it.
1. I started growing using PMix, a good medium with the proper amendments. Make sure you get some dolomite though, maybe even some ag-lime, but be careful with it, that stuff is strong and can burn the plant. PMix will become more acidic over longer periods of time. If you use it just to start plants, or during a short veg it should be ok, but if you intend to run it the entire long-season, then use dolomite.
Also, PMix can dry out pretty quickly, and ounce it's totally dry it becomes like a big pete pot (jiffy pots). PMix would be my last choice, but I'm not saying it's crap, just my least favorite.
2.
FFOF is a good soil in my opinion, I used to cut it with PMix @ 2:1 (OF/PM) And still had good results. The only problem I encountered with
FFOF is it's a little too hot for young plants, unless they're hardened off. Clones can handles it a little better, but still. So if you cut it with PMix, which is way cheaper that
FFOF, it could make a little bit of amended soil go a long way.
3.
Roots Organics I really like, it's a little cheaper than
FFOF, I think the micro life also likes it better too. Also it's not too strong on the amendments, my Afghan is in straight RO with an occasional feeding of EJ, and with no major deficiencies at least until about 45 days then I would top dress a little with some guano, bone & blood meal, glacial rock dust, kelp meal, and a little dolomite.
I've never had a tainted batch of soil yet, but I've heard of stories similar to Martys in regard to fungus gnats, but on the other hand.... Contrary to what Marty said, I've had fungus gnats invade my PMix-only-grows.
I hear Black Gold is actually a pretty decent soil, and so is Sunshine mix. Ohana Greenhouse actually started stocking Dr Earth products, I don't think they have the full line, but you should inquire about DrE soil. I've heard that it's recipe is designed to cater to cannabis, that's why it's called Pot-ting soil, I believe it also says it's for medical gardens. Of course I'm reading between the lines, but it's pretty obvious.
That's just my $.02
Aloha, Fats