Onions from seed?

My onions are looking like they are almost ready for lifting, I have onions from seed, sets and heat treated sets, all looking about the same size, possibly I should have watered them a bit more, but not a thing I usually need to do, this has been an exceptional year and the ground very dry, had one or two running to seed but was more vigilant this year and removed any seed stalks right away, my garlic bulbs are not as big as usual but still ok

Does anyone have a recommendation / favorite onion for storage, red as well as white?

Still trying new varieties from seed. Red Brunswick keeps well but its red outer skin and white inner. Zebrune keeps very well. Bedfordshire champion is meant to be a good keeper but doesn't store well for me so I start taking early

Santero F1 is a good onion for storing

For white onion sets, I've bought sturon and 'stur bc 20' from Bridgend Nurseries in Scotland somewhere as they sell a lot of seed potatoes also. I've had them for a few years but didn't keep separate to see which kept the best. I was going to last year but they arrived in paper bags that burst and mixed in the box so I couldn't. What I do know it I still had some that were reasonably firm on 1st July this year when I lifted my autumn planted sets. They both have a reasonably strong flavour.

So I sowed a couple of vararities in Jan, yellow onions good germination red poor.

Question for today is can they go out into the cold frame now or is it too early? TIA