I used to the the ones for Marketforce since I shopped at that store anyway, but for what they paid, I wouldn't go out of my way.
Northfork has one chain in the Northeast that I would do if bonused. Then they got some editors that made in un-enjoyable to submit shops, I don't think they never did a shop in their life. One store didn't have a bakery and they fought me on this issue. Finally they relented and told me I should have taken pictures of the baked goods on a table somewhere in the store.
They also questioned one of my pictures stating it was out of focus. I asked them why I could plainly read the sign at the farthest distance in the picture. Their reports are also long for the amount of pay and reimbursement without a bonus.
Pricechopper is also shopped but I don't recall the MSC. I did one of them and it seemed like too much work for too little pay.
All of them seem to have you interact with someone in each department in the store. I've noticed that many of the meat departments, the butchers leave by five and it's almost impossible to find somebody in produce.
Another pet peeve is you need to get each person's name you interacted with. One store they all had nicknames on their badges like "T". One employee had two different badges one when he was working customer service and a different one when he checked me out. And many of the employees would wear their badges on the side of their hats so you would be obvious trying to read the name if they didn't turn their head the right way.