I have the Detours Toocan bag.
It's pretty nice and I've gotten lots of use out of it.
But note - the bottom is not "welded" to the bag, and consequently it's limited in the weight it can carry ... something like 12 pounds max.
Some pros: It's super-easy to load on and off the rack. It's fairly roomy.
Some cons: Limited cargo capacity (weight). Pockets are not terribly useful, in my opinion.
I've never used it for groceries, but I imagine it would be pretty good to cart into the store and load your purchases up right at the checkout. As long as you aren't buying gallons of milk, I suppose.
Oh...and the last con....
Your TE friends will razz you no end about your old lady "carpet bag!"
Oh...maybe that's just me!