I worked at Uniqlo back in 2018 and while working there I bought like 10-15 of their basic suprima t-shirts. I'm still using them daily. For a 10-15€ shirt (sometimes there are sales), I don't see a point going for something else. Fit is pretty consistent across colors and years, light but not cheap feeling, good color options.

Quick edit: I'm in Germany, thus Euro, but they have stores in the UK too