Tasteless leathery onions

Im really disappointed with my onions this year. Not withstanding all the problems with leaf miners - the couple I've used so far have been very sharp but also tasteless. 

They were Stuttgarter Riesen sets from Bakkers, and have very little flavour and rather are hard and leathery, being flat they're also really hard to slice for cheese sandwich.  Last year I tried Setton but they didn't get bigger than an egg although  better tasting they weren't overly impressive.

Im searching for something that tastes like an onion should, people keep telling me that distance lend enchantment and the taste I remember doesn't really exist - but there has to be something better than these.

I never found stuttgarter a nice onion, it's too strong and not particularly large. We've switched to Candy onions we grow from seed; it's a sweet onion and keeps reasonably well through winter, much better than the white spanish we love and grow as well.
They really do need lots of feed either as manure or liquid feeds like comfrey, and well developed soil and regular moisture. Otherwise, they're pathetic.
There's always next year now that you have some good tips.

I planted Stuttgarter Giant sets from Wilkos and they are very large, flat bottomed and tasty.