It depends on what you want, really.
If you want a Leica, nothing will replace it. Even though on paper there are many much more capable alternatives.
So if the end goal is a Leica, just grit your teeth and buy a Leica. You would be happier in the long run.
If you are really on a shoe-string and still want a Leica, you can always check out the Leica CL.
Technically it's still a Leica and it's a very nice and nifty camera, you can use it with the CV 40 1.4.
If you are looking for a true user camera then look no further than the Voigtlander Bessa range.
They may not feel as refined, prestigious, hefty, substantial or silky smooth as a Leica, but they get the job done.
That is not to say they are clunky machine either.
The Bessas are beautiful in their own way and handles well.
Furthermore, the Bessas have the added benefit of being much newer and still in production (
excluding the Leica M7 which you still can buy new).
That means they generally have less problems and when faulty, repairs are much more convenient.
Depending on your preferred focal length and whether you need AE.
You can consider the R2A, R2M, R3A, R3M, R4A, R4M.
'A' being the ones with AE and 'M' being manual, but still having a built in meter.
If you are keen, you can read about the differences between the models
HERE.
I would recommend going for the newer R2M/A over the older R2.
The differences include rewind crank, eyepiece, diopter, viewfinder display, 0.7mm minimum focus distance and metering pattern.
Overall, in my humble opinion the R2M/A are better cameras compared to the R2.
A rung above the Bessa, arguably, would be the Hexar RF and Zeiss Ikon.
Both are very capable cameras and highly advanced, they also have the moniker of being the poor man's M7.
Among their features are AE, motor-rewind on the Hexar, fantastic viewfinders and 1/4000 top-speed on the Hexar.
If you are willing to shell out a bit more, do consider these fantastic cameras.
The Zeiss Ikon is still being serviced by Cosina (at far as I know).
The Hexar would be slightly more difficult to get serviced.
For the fixed lens, affordable options, it's already very well covered in the above link.
The Canon QL17, Yashica GSN, Lynx and others are very popular cameras.
However, they are still old cameras and need some tender loving care.
And there there are the Nikon rangefinders and various Canon models which warrant another whole essay.
But essentially, these are your options. I sincerely hope it helped.