all different brands have different cut even though some may be made in the same factory. In a sense ignorance is bliss, a little knowledge can be dangerous. So here is some knowledge,; Off the peg or RTW is limited to simple alterations like waist of trousers. As soon as you alter sleeve lengths on RTW you tamper with one of the 2 good things aboout RTW, the finish. The price is of course the other.
Made to Measure is the next step up and the human factor comes into this a little more. You are now dependent on the observational ability and knowledge and integrity of the person measuring and the complexity of the system of measures.
MTM has limitations in that the inlays for manipulation are limited and in my opinion the sleeve mostly is fairly generic in that it lacks a shape and style and will be usually cut with a fairly generous false forearm and they always look a bit pipeish as they have to fit most people mostly but not anyone absolutely.
Most made to measure suits lack chest and are generally crooked in cut , resulting in the hips relative to the shoulder and chest being larger ie a more feminine proportion in this area rather than that of a man. A lot of people on the forum defend this as open quarters though what this really is, is the straightening and crookening of a coat. A straighter coat is much harder to fit. In the bad old days all coats were fairly crooked as they came about from the frock coats. a morning coat and tails are correctly more crooked than the modern suit, the suit jacket originally referred to as the 3 seamer some time before the 1860's. Open quarters seem to be making a comeback if on nothing else than the growth of the poorly cut suit or the inexperience of decision makers of style to know any better. A crooked coat will never button up well, it will always be fighting with the buttons and so many other things that it would be an essay and not helpful.
The strong point of MTM is that you will look like a lot of other people and in a place where difference is not always celebrated it may pay to be a little generic.
The finish of a MTM will always easily rival a bespoke tailored suit for finish outside in inside.
For some the inside of the jacket is just as important as the outside. Ask yourself this however, are you a person that likes to show off the inside coloured lining of your coat around the water cooler? Or walk around with the bottom cuff working buttonhole undone just so as people know that you have working buttons on the cuffs of the sleeve.
If the answer is no, then your mind is free to concentrate on the most important thing about a suit which is the cut and the fit. And with Cut and the fit, bespoke will win this one hands down. As a bespoke tailor and cutter I have a bias towards Bespoke. However I got there after a long career in selling everything from a local suit to Zegna Valentino etc, and over a decade and a half decade of MTM under 4 different systems.
Bespoke has its limitations. Not all tailors and cutter are good, some tailors become lazy, can't blame them it is a hard career ( though satisfying for the right person) apprentices may not work out, if Bespoke is the pinnacle then you are needing to conquer very high expectations, battling against the million dollar marketing campaigns of brands, it is a laboring job, the cutter develops the good client relationships, constantly battling the most ridiculous fashion influences . The daipered seat of suit trousers appearing below the coat is a good one right now. If only the suit wearer could see ass cam 5 yards back walking behind, they would ask for a longer coat.
A big limitation is in communicating the cut to the first time customer. With MTM and off the peg you can roughly see what you are getting, with bespoke you will need to bridge the gap. All bespoke coats are made differently, the best ones however are a work of art. And if you are as fortunate as the poster Paddock who in posts on " The Best Bespoke in the world" or something like that, in that thread insists that money is no object, then go for the best, and that will be bespoke but the jury is out on who that is. I think get a suit cut in Savile Row and get it made by a tailor in Italy.
I hope that there is the odd thing of help in here for you