This is a really good question and unfortunately the answer is not black and white. Although we can measure HD in terms of lines (720, 1080...), it is difficult to measure 35mm film since it is analog. In one of the studies that I have read, HD is ve...
Canon and Nikon 35mm SLR's would be a good choice because you can find not only good used cameras, but good used lenses for them ... the added feature is that if you ever do purchase a DSLR, all the lenses you have will fit their matching DSLR body.
Just like there is a mask for the 6x4.5 there is also a msk you can get for the 35mm to avoid exposure on sprocket holes. site that shows how to shoot 35mm with holes being exposed: site where you can buy 35mm kit with mask;