Tailor on Ten
I recently visited Tailor on Ten and was very impressed with the overall experience.
Had two suits, some pants and a bunch of shirts done and am very happy with the results. Went with the mid-range quality fabrics which seemed like the best option for me (though some of the top quality materials looked really nice, but obviously are more expensive). I chose the 100% premium cotton shirts at 1700 Baht each which are really comfortable (IMO if you have some shirts tailored, it´s a waste of money spending it on a cotton/polyester fabric) and the super 100´s pure wool suit at 12k Baht each (the price includes one set of pants).
IIRC I had three fittings, I´d definitely recommend to have enough time to have several fittings as they like doing some small changes here and there which obviously contributes to a better overall result.
What distinguishes them from their competitors IMO is that Ben and Alex (the owners) originally come from Canada and not only speak English fluently, but are also familar with the "European/American style". The other two members of the team - Kevin and Paul - also did an excellent job and were very friendly.
The only minor inconvenience was that they only accept cash as payment, but they do accept CCs when you order more stuff through their website.
I was very happy with the experience overall and would definitely recommend them.