My clothes that have stretch fabric are much more comfortable and seem to allow for a slimmer fit while still being able to move.

I want to start dressing better and buying clothes MTM but I am having trouble finding stretch fabric options, for both pants and shirts.

Am I right in the assumption that stretch fabric will suit me better? or is it possible just getting a better fit with MTM will suffice?

The reason I'm leaning towards stretch fit fabric is because I am fairly muscular. I have not been able to find pants that are slim enough around my thigh while not feeling like they are going to rip at the seems when I sit down, unless there is some stretch in the fabric. Even 2% lycra makes a huge difference. And then with shirts in general while moving around there is always something pulling and tugging.