To understand why printing comes off of cheap T-shirts, see CottonBureau's excellent comparison of screen-printing and "DTG" spray-on inking processes.
Expanding on that - what's your go-to T-shirt shop inside the EU? Ordering from Threadless (US) to the EU is quite expensive (shipping + taxes) and I haven't found a quality EU alternative yet.
Spreadshirt? I've used it quite a lot and found it to be good quality, haven't ordered for about 18 months from them. I've got decade old stuff from them that's still good.
I usually go to qwertee (https://www.qwertee.com/). As I've said in another comment I've had some minor sizing issues but the print quality is decent enough.
I am looking at Qwertee and want to find out about their business model and designer compensation, but whenever I approach the page footer, a new batch of T-shirts thumbnails is loaded in the page content pushing the footer away…
Someone didn't think that one through.
Edit:
> Artists/Designers receive 1 Euro per shirt sold or USD or GBP equivalent. You also retain all rights to your artwork before, during and after it appears on Qwertee (most other t shirt design sites want ownership of your design forever).
I'm living in Russia, we don't have any extra taxes. Actually, we have a lot of local clones with the same prints from Threadless(of course illegal), but a price and quality worse than Threadless.
I switched to http://www.fangamer.net ages ago because of quality issues and didn't regret a thing. Even if you don't know the video games references, they're good looking.
I'm a big fan of https://www.designbyhumans.com/ for their cool designs (they are constantly adding new ones). Their website is also pretty nice and they frequently have discounts.