Ha!!! I have not tried uniqlo tees, but I do love their merino pullover/lightweight knits (not for summer though! )
Madewell was my go-to for boxy tees, but I have fallen very out-of-love with the fit. They are not cropped, but they fall at a weird place on my body and I find myself always tugging at them... I tried a size up, but the shirt is just wider; not larger all over. *shrug*
I just purged a handful of madewell ones in favor of some men's tees from H&M. They aren't the highest quality, but they are thick enough to hide my bra and so far, they are washing and wearing well, without obvious pilling or fading.