Sweetcorn - good so far! Amazed how quickly the kernels grow after pollination. Never grown it before but kernels on some cobs are starting to ripen already.
Lettuce - couldn't eat it fast enough, did well throughout late June/July in two planters (interspersed with corn).
Zinnias, cornflowers, rudbeckias, and other flowers such as salvias all done well after a very slow start. Sweet peas flowered beautifully (but rather late - we still have flowers on one plant). Kept picking them daily and seemed to work.
Sunflowers very slow to get going and got badly munched by snails in the spring but are just starting to flower now.
Courgettes were OK but didn't last long (all got powdery mildew and couldn't keep on top of it). Got one fantastically large plant which produced ~15 courgettes which we all ate and enjoyed.
Tomatoes have been rubbish! Pretty sure they have blight now. Managed to harvest one huge beef tomato last month, and some small yellow cherry ones recently, but the rest are refusing to ripen and are slowly rotting.
Broad beans - after a bumper year last year they all got mouldy and sad in the rain this year. Didn't harvest any.
Peas - all got munched before could harvest.
Carrots - 50/50, some were great and tasty (but not as large as last year) and others bolted or went very woody.
Parsley - was great as soon as it warmed up properly in July, but has stalled now
Rocket - completely stalled
Pak choi - has germinated but stalled as well
Quinoa - I doubt this will work, first time growing it, but the one in the planter is still growing and seems to be seeding whereas the one in the pot has stalled quite a bit
Basil - terrible. Got a few small plants going in the large planters but they got munched then stopped growing after the last mini heatwave.
Peppermint and spearmint - again really bad! Seemed to get that white fungal infection then went straight to flowering.
Wow, I grew more than I'd realised 
it's really been hit and miss this year.