Hey Happygolucky, Hey Tom - welcome to Purrs!
What a very good question to ask, and particularly pertinent.
Have you seen the recent news about the recall of AVA cat food products in Pets at Home? Insufficient thiamine in the food led to cats falling dangerously ill, and perfectly illustrates how easy it is even for pet food manufacturers to get the balance right.
And a difficult one to answer. In essence, you're looking for a wet food with the highest meat content possible and as few artificial additives, especially grains and cereals.
Arguably any decent wet food is still better than dry, as it's closer to a cat's natural diet, but check out products such as James Wellbeloved, Applaws and Lily's Kitchen for starters. Also Cosma. Other members will be able to recommend alternatives to look at too, including a raw diet if you felt brave enough.
Of course, the real sticking point with this kind of search is whether your cat will adapt to the food you pick out for them. Cats are notoriously choosy when it comes to the food we slaves give them, and you can spend a small fortune on food which is "best" for them and they'll pin you to the ground with an icy stare for such impertinence as to meddle with their nosh.
How about Tom? What does he eat now? How old is he and how long has he been in your family?