Summitar got noticeable comma up until ƒ/5,6, collapsible Summicron is a bit better, I am talking about good samples not dog lenses.
The Elmar ƒ/2,8 is very interesting lens but LTM Elmar ƒ/3,5 got unique rendering due to diaphragm position after the the 1st element and other optical specifics, also a much smaller lens than anything 50mm Leica.