IME, as long as you get the angles right, and you are neat and precise with your cutting, a mitred corner looks much neater than an oversized L piece.And if your installation isn't to look crap, you need to keep this small gap consistent along the run.
Ditto butt-joint Ts vs oversized T pieces.
More work though, as is often the way. cf plumbing done in copper pipe vs plastic push-fit.