So I've talked about the longevity and the specificity.
But the most important one is fit.
If you are lucky enough to be perfectly in proportion then stop reading now. Continue to happily and successfully buy glorious RTW suits that fit beautifully. You don't need me.
But if like me you are not, then do not feel bad. Most people have one arm longer than the other, or a long back, or short legs, or a dropped shoulder or broad back or narrow hips... You get the idea.
Ready-to-wear clothes are based on the measurements of a fit model and then scaled in direct proportion. So the assumption is that if you have a 44" chest then you will have 36" long arms (for example).
For a lot of people the differences are subtle enough not to matter too much. But if you are a rugby player, or a musician, or a builder, or anyone who has done something physically demanding for a large stretch of time, you may find that there are more obvious discrepancies.
I have a customer whose left shoulder is much lower than their right meaning that an off the peg jacket sags on one side if left undone, and gapes at the neck if done up. Or there is the violinist who has one shoulder an inch smaller than the other after years of holding the instrument. Or the man who has one arm much further forward than the other. The list goes on.
One of the biggest differences between Made to Measure and Bespoke is that the pattern will be drafted from scratch specially for you. Meaning these quirks will be taken into consideration. The left and the right will be cut separately if needed.
If getting something made from scratch seems like a daunting and expensive task, then why not just take RTW clothes to a good tailor and have them make a few tweaks. Even one or two simple alterations can make a world of difference without costing the earth.