I agree with @Patrick06790 on Mercer. Every aspect is perfection: The collar of course (not just length but also button placement), the (slightly narrower than others) yoke, the billow of an absolutely perfect weight cloth, the button placement on the placket, the lapping of the seams, the two knife pleats rather than the Brooks pucker at the cuffs, the length of the tails. I view Mercer as every bit the equal of a custom shirt. They will make any aspect to your specifications, not just collar and sleeve length. Lastly there are colors. Their blue is much akin to to old blue grey of Brooks, and their pink is softer and more versatile than the darker pink of Brooks. To me the only fault with Mercer is lacking an ecru, but someday I may get a swatch of the cream.
Looking into history I also loved the Gant Hugger of the 1960s. It had a slightly slimmer cut, hence the moniker. It had the same details as Mercer plus a locker loop, a split yoke, a button on the back of the collar, and stitching around the cuff that intersected at the button hole rather than the usual 3/8" down from the top of the cuff. They were nice enough touches that I recall them readily.
Looking into history I also loved the Gant Hugger of the 1960s. It had a slightly slimmer cut, hence the moniker. It had the same details as Mercer plus a locker loop, a split yoke, a button on the back of the collar, and stitching around the cuff that intersected at the button hole rather than the usual 3/8" down from the top of the cuff. They were nice enough touches that I recall them readily.