We used wegoshop during our last trip and had a very good experience with them. And we're going to use them again in April!
The advantage to using wegoshop is that you can select the brands you want purchased... you essentially give them your shopping list and they will go to the store you select. With Garden Grocer, you are limited to their inventory.
I've read good reviews about both, so I don't think you can really go wrong.
Have fun!