Bloke here.
Check out Under Armour Boxers. They are by far the best I've had. Next to no seam on the inner thigh, comfortable, stretchable they are awesome. They are slightly more pricey. 2 pairs for around £20 on Amazon but worth every penny. After I tried them I spent £200 and threw every other pair of boxers in the bin. That was 3 years ago and I have never wore a pair out yet.
I will say I have Skin Grafts on my legs and used to get a lot of chafing on sensitive skin but not with these.
Worth every penny.