Aria is smaller than the RX and the RX is more robust. I like my 2.8/28 mm and especially the 1.4/85 mm. The 85 is quite large and the 2.8/85 and the 2.8/135 are cheaper alternatives. Especially the 135 is exzellent! These Zeiss Contax lenses are not more expansive than Nikon or Canon of comparable quality! Leica is more expensive! I am using Contax bodies 167MT, S2 and AX since over 20 years and i will continue to do so, hopefully for another 20 years.