I've been using the Canna line for most of the last year and I've no complaints. Canna is the only brand I've used though so I have no comparison to say its better or worse than the others. I use only their Rhizotonic (only for my clones), Cannavega (for in veg) and Cannaflores and PK13/14 for during flower. I add molasses instead of their overpriced bloom boosters.
I've found that the feeding schedule is different for other parts of the world which is a little annoying but I just checked my bottles (and the schedule) and in the Netherlands at least it says nothing about needing to let the mixed water stand for a couple of hours. I have never done that myself, always mix and water pretty much straight away. So I would say its a case of reading the bottle you get with regards to that.
All in all I'm happy with Canna and have never felt the need to change. It suites both me and the girls, and so long as the girls are happy, so am I
Disclaimer: Everything I write is simply virtual roleplaying. Life is but a play, so lets play.