The Q3 43 combines everything that I need for my personal style of photography at this point in my life. I have used Leica M bodies, film and digital, for decades. I bought the M's so that I could use the wide variety of superb Leica lenses. Lenses in the 'Normal' range of 40-50mm have always suited my personal shooting style best. My two go-to lenses for walking around are a APO 50 and an old Summicron-C 40mm. The Q3 43 is the sweet spot for me.
I live in the Pacific Northwest where it rains a lot! The Q3 43 is weather sealed, my M11P, M11M, M6 and M lenses are not. My 80 year old eyes make manual focusing difficult. The Q3 43 Auto focus works great for me.
For me, the Q3 43 is the one camera to carry when I only want to carry one..your mileage may vary. And, the cost of the Q3 43 is only 45% of the combined cost of a M11P and APO 50mm!