Online shopping deals

What are the best websites for deals you've found? Do you find it cheaper to buy online or in stores? I've used Amazon sometimes, but sometimes it's more expensive than the store, or I just get confused trying to figure out the prime, pantry, add on item, subscription etc rules. I'm looking more for everyday shopping, not large purchases.

Do you have any great deals especially for groceries/pantry stuff, pet supplies, toiletries, or cleaning supplies?

Thanks!