I've decided to sell my Leica M 50mm 1.4 Summilux Pre ASPH to fund another lens I need more for work. However, I've been thinking about two other FL's in the M mount. The 90mm Summicron or the Elmarit 90mm and the 35mm Summicron. Does anyone have a preference for the best formulas and production dates? I would use these on my M2-R. Thanks.