I own all three and another (iEDGE) is on the way.
I am using Transcend memory in my Cyclo/EDGE twins and Kingston in my AK2i.
I have an iEDGE on order and another Transcend microSDHC for it.
I have had problems with the (non-identical) twins with the Transcend cards, but I do not know where to place the blame, on the memory or the flash cards.
The AK2i has the best and fastest support (AKAIO team), EDGE has the worst, but better than all others.
My personal overall preference is EDGE, EVO, AK2i, but I would only recommend AK2i to a friend or relative.
I like the simplicity of the EDGE and support is adequate. I have been using an EDGE for forever.
I hated the first acekard and didn't try another until the DSi. I tried AKAIO and I like it!
AK2i is the cheapest, it has the best support and it was the first card that I could play HGSS without problems.
Plus it works perfectly in my new Bronze DSiXL!
Bottom line: Buy an AK2i unless you have already established a preference for Cyclo or EDGE.