Hello,
I have several Kievs (2, 2a, 3a, 4, 4a, 4am) from the 50ies to the 80ies. I have a very good working 1952 Kiev-2 and a good working 1982 "4am". My 1957 "2a" is not working well (even though I shipped it to Oleg fo repair) and my 1967 "4" has got a broken shutter. This story could go on and on...
Many tend to say that early ones are build better. I would agree that a Kiev-2 has a better finish than a 4am. But the "2" is already 50 years old, and you never know who had it in his hand bevore.
For a good user cam I would go for a simple 4 or 4a from the 60ies or 70ies or also a later 4am or 4a from the 80ies. The early 50ies cameras are often quite expensive.
If you have the money and patience you could search for a "5". The "5" is bigger, but has a wounderful finder, which can be used for lenses from 35-85mm, so you do not need an extra finder for interchangeable lenses
Regards,
Andreas