ive got several NN sets, ive tried the flannel when there's been the occasional plain design but theyve all gone back or been given away. just too hot for me.
i prefer the high Tc ones but beware, theyre made in lots of different parts of the world and the quality can be very different across different sets. i have a tsv once and it was so thin you could almost see through it, despite it being 350TC. so if you order and dont like it, dont let it stop you trying again another time if you see something you like. i always buy white so cant comment on colour fastness. i always wash at 60 degrees, yes they crease but if you take out of the drier, fold and put somewhere warm for a day or so they dont need ironing.
the best one i ever bought was called "Timeless Stripe", its got a very subtle dobby stripe in it. it's so good i bought another identical one shortly after. if you just wash and tumble dry it feels soft and warm like talcum powder, but if you iron it goes crisp and smart like great hotel linen. best NN buy ever.