Both my boys absolutely love these underwear! For reference, one is stocky and thicker, the other is lean and strong - - but they're the same height. Both wear size S in this brand.
Things they like: undies look like dad's, fit well around both waist and thighs (had problems with other brands loosening in the leg over time and with *ahem* parts flopping out and about on the skinny child), they like the colors, and they say they're comfortable.
To boot, I got them on sale this time and so they were cheaper directly through Mallary by Matthew's website than through Amazon, which is where I encountered them first. I'm trying to steer away from Amazon these days, so I was really excited about that!!
I highly recommend!!