I must have tried most, if not all, of the plant-based *barista* milks on Skroutz in the past year, for homemade cappuccinos & flat whites. Several products were decent (e.g. Ecomil) but the two that stood out for me were Sproud barista (be careful, the non-barista ones are much worse in coffee) and Oatly Barista. Of these, Oatly is the best because its taste/smell doesn't tire you out and you can drink it every day (I really like the Sproud chickpea one, but you get tired of it after a while). Consistently good frothy milk, thick, neutral aroma/taste so as not to overpower the coffee, with a slight plant-based sweetness if heated to the right temperature (57-60°). Try not to exceed 65° with plant-based milks (ideally ~60°).
p.s. It is often available at a well-known supermarket chain at a good price (~3.15€ last time I bought it).

The only thing that makes perfect frothy milk, either hot or cold. I have tried many, this particular one ALWAYS gives a professional result.

The best thing for hot drinks like coffee (it also makes good foam) and tea! I can't have milk from animals anymore :)