I usually find tomatoes bought in winter to be a bit insipid. I look out for the labels to make sure they come from as far south as possible. Just had some nice cherry toms on the vine from Waitrose that were grown in Sicily. Shops ruin tomatoes by keeping them cold. Low temperatures switch off genes that promote the production of those lovely tomatoey flavour volatiles, leaving just sugar and acid tastes. The genes don't switch back on even if the toms are warmed back up. The worst thing is to keep tomatoes in the fridge. Another tip is, when making tomato soup or tomato sauce, to add half a teaspoon of sugar. The Italians do it all the time even though their tomatoes are lovely already. It works - don't ask me why! I've found that tinned plum tomatoes are just as good as the real McCoy most of the time for sauces and soups. Supermarket brands can be a bit chemical and stalky and I'm particularly not fond of Morrisons. My favourite brand is Cirio - very reliable with good, thick juice. Napolina are OK too.