Eh, I don't know why everyone thinks the Canonet GIII QL17 as being great, I have one, have it CLA'd, used it, not blown away by the result at all, rather flat and not very sharp.
The S3 has nicer bokeh, the Olympus 35 SP has sharper lens, only the quickloading and the heft make up the positive points for it.
And the Canonet is bigger than the S3, I think the S3 or the similarly sized Minolta Hi-Matic 7SII are the best if you're going for small camera (the Oly 35 SP is even bigger than the Canonet, but not bigger than the Yashica Electro).
Now batteries, the Konicas (S3 or C35) can use Walgreen-branded 675 hearing aid batteries without problems. I've read using aluminum foil to pad the battery on the Yashica works (I've done something similar for my Olympus 35 EC, so I knew it *could* work).