I buy only organic tomatoes. The most expensive ones available at the supermarket.
Have been doing that for years. Stopped buying the big (normal) ones years ago because I couldn't come by any with taste left. Went for the smaller ones. Most of those were good for some time, than they declined also. Now they have micro tomatoes. The one time I bought them, they tested quite good. Can't find them anymore. Maybe it was a one time thing. I grow my own on the balcony now and rarely try to buy any in stores these days. Sometimes you get a good batch. Most of the time it's a waste of money.
The only way to get good ones for sure besides growing them is buying tinned ones and probably on the market but I work and have no time to go to the market.
I'm in the UK, ymmv, but I'm happy with (especially British-grown) 'San Marzano' large plum tomatoes.
Especially in-season they're often in the (great value) 'tomato selection' punnets that at least Waitrose and M&S offer. (The rest are a mix of whatever their buyers found reasonable, typically mostly small cherry and plum.)
I'm absolutely not claiming they're the best, they're not, but the value's great (~£2.70/750g iirc) and there's flavour. Anything cheaper is flavourless crunchy crap IME. (And plenty more expensive too, I don't really understand, but I suppose the unpredictability of what's in the punnet is helpful/a saving to them, so it can be made cheaper to consumer? :shrug:)
The only way to get good ones for sure besides growing them is buying tinned ones and probably on the market but I work and have no time to go to the market.