Seeing that you already have a Nikon system, you might want to explore a higher-priced rangefinder system. If you don't want to spend a fortune -- yet or ever -- you can try the Cosina Voigtlander bodies and lenses, which give you the interchangeable-lens rangefinder experience on a budget.
The Cosina bodies have very nice viewfinders. Make sure that the rangefinder alignment is good.
If you buy used, you probably can pick up a used body and two lenses for a fraction of the cost of a single new Leica lens (or certain Zeiss lenses).
Of course, a Cosina isn't a Leica, although they are very good bodies.
If you really enjoy rangefinders, you can continue to build out your system or move up to the higher-priced gear.
And if you don't enjoy the experience, you probably can sell the gear for the same price you paid and get out without a loss.
But find what works best for you.
Lately, I've been using SLRs with a sidetrip to an Argus A2B an several other viewfinder cameras. Still love my Contax IIA.
The Cosina bodies have very nice viewfinders. Make sure that the rangefinder alignment is good.
If you buy used, you probably can pick up a used body and two lenses for a fraction of the cost of a single new Leica lens (or certain Zeiss lenses).
Of course, a Cosina isn't a Leica, although they are very good bodies.
If you really enjoy rangefinders, you can continue to build out your system or move up to the higher-priced gear.
And if you don't enjoy the experience, you probably can sell the gear for the same price you paid and get out without a loss.
But find what works best for you.
Lately, I've been using SLRs with a sidetrip to an Argus A2B an several other viewfinder cameras. Still love my Contax IIA.