I have own or owned the following:
Zeiss Contessa (folding)
Minox 35GT
Olympus Trip 35
Rollei 35 made in germany
Agfa Karat IV
Electro 35 GSN
Electro 35 GL
* Olympus 35SP
Olympus Pen S3.5
Kodak Retina IIIc
* Walz Envoy M35
* Fujica 35EE
Voigtlander Vitoret DR
Voigtlander Vitomatic Ia
* = unusable for now, they need repair
From all the list my favorite is the Kodak Retina IIIc, it is just superb.
The best lens in terms of rendering is the one on my Agfa Karat IV
I liked the Electro 35GSN, it had the right combination of everything except for manual mode and compactness.
Of the ultra compact cameras the Olympus Pen S3.5 (half frame) is my favorite -- tiny, well built, all manual, great lens. The Minox 35 was great until it died. I replaced it with a Rollei 35 -- big mistake. The Rollei is cumbersome to use. Sold it.
Moving up in size i just bought and restored a Voigtlander Vitomatic Ia, scale focus camera, and I think i will love this camera.
The best viewfinder and rangefinder is the one on the lowly Vitoret DR, believe it or not. Once cleaned, it is big and excellent.
The top cameras in terms of build quality are:
#1 Voigtlander Vitomatic Ia and Zeiss Contessa
#2 Kodak Retina IIIc
#3 Walz Envoy and Agfa Karat Iv and Fujica 35EE
Olympus 35SP is my favorite 35mm camera. The outstanding lens, light weight, spot metering, and exposure lock make it the easiest to use of any of my RFs.
I have yet to repair the 35SP but so far the build quality is below my standards, the shutter button is horrible in travel and feel, the sound is too loud, and the shutter vibrates more than acceptably for a central leaf shutter. The viewfinder is unremarkable.
I want to love the SP but i can't help but feel it has been overrated too much on the internet. Yeah, i know, the lens -- but i have wonderful lenses on the Fujica, Vitomatic, Walz, and Agfa as well.
On the other hand the Olympus Pen S3.5 is everything a good Olympus should be, including smooth and well built. The lens is excellent, unit-focusing, focusing collar is smooth, all manual controls easily available.