Marcello's IN the Galleria used to be great, but they have not done so great of a job lately, so I stopped using them. So its not really a recommendation, more of a warning. I haven't found anybody else yet because I haven't had the need, but your thread brings up a good topic.
There's a place on the southwest corner of Sage and Richmond next to the Ruchi's that does good work and is very reasonable.
Phnom Penh Tailors has been around for years are well known. It's off of milam in midtown. It's alittle asian ran shop, but they are known for good work.
I went to Saigon Tailors on Alabama and they did a terrible job on some pants that just needed to be hemmed. Spoiler I complained and they did nothing, so I took them back to Nordstrom to have them fixed (for free)