I need a good arm to mate with a modified Lenco L75

You planning to use any particular carts? Might help refine the answers! 

I love the sound of my vintage ADC XLM II Improved. It is currently on an SME 3009 Imp/Thorens 125 II. My only experience with MC cartridges was a Denon 103 which I was not impressed by in this set up. In my reading about cartridges it seems there are some folks who feel that even though they are cheaper as a group MM is a superior format to MC. I don’t have enough experience to know how true that is but in my limited comparison that conclusion is certainly born out. Does is make sense to pick the cartridge first and then the arm or the other way around?

@noromance 
Cant say for sure.  My Van den Hul black beauty sounds great on the VPI with ET II arm.  My Lyra Delos on the  301 with Ortofon arm sounds equally as good.  These are very different sounding rigs but each has its strengths.  The Delos was bright in the VPI/ET but not on the 301/Ortofon.  Have not tried the VDH on the 301 yet.