Inhave used wheeled shopping trolleys for some years. Mainly just the 2=wheel type. Before I moved to my flat I thought long and hard about how I would do shopping. Although I had a car, I needed to work out how to get my weekly shop from thecar upstairs to my flat..
Did a lot of research, and finally decided to go for a large 4-wheeled bag, that folded down when empty. When I had my car I found that I could not get this in the car upright when full. So used to do my shop with two large normal bags. Once back home, these bags were then put into this trolley for me to wheel upstairs.
No car now, on the occasions I go to the supermarket on the bus, this trolley is excellent, and I shop directly into it (using the zapper). Obviously on the way home I cannot fold this bag, but have never had any problems on my local bus. When I get home deliveries, I take this outside my front door and just put everything into it and then wheel into my kitchen.
It is very much and individual choice. In the past, the smaller ones were fine for me when going down a market. However, I find this bigger 4-wheeled one is far better and I can lean on it and use it as short term walking aid. It has a place in which I can place my folded walking stick. It has a cover, so when full of shopping can cover it all over.
It was quite pricey (around £80 three years ago, but I am very pleased with it. On the few occasions I have to take it up and down kerbs it goes over those with ease.