The Yashica 44's come with a number of different lenses, and there's some controversy over the relative quality. Different sites say different things, and the issue is confused because often the sites are refering to Yashica TLR's in general rather than being 44 specific. This is what I've collected from looking at all of those sites, and examining the Yashica 44's that I own.
post 1:3 element Yashikor is rubbish - I'd never go near one.
post 2:I've used them and they're fine.
post 3-10:I've got one too and its great.
Trying to resolve this into some kind of coherent picture, it seems that Yashica three element lenses have a bad rep, based on the Tri-Lausser and Yashimar lenses. As a result there's a lots of advise to avoid the Yashikor, but in fact its not so bad, and many people are very happy with their performance.
The Yashikor 3 was used on the early 44's (with the winding knob) and on the 44a's. Given that 44a's can be picked up for around 40 pounds there doesn't seem to be a lot of reason to stay away from the Yashikor lens.
Yashicor four element lenses were used on the 44's which have the winding lever. In principle you can check this buy opening the shutter on the bulb setting, with the aperture wide open. Hold the camera up to a bright light source, and count the number of reflections you can see - there should be two for each element, so there will be either 6 or 8 depending on the lens you have (as can be seen very clearly in the image above). However as the Yashikor is a three group lens, the fourth pair of reflections might be difficult to spot.
Having established which lenses are in which cameras, the ultimate question must be "does it matter?". Given the prices at which these things can be picked up on ebay, it probably doesn't. On the other hand if you're paying out big money for a dealer reconditioned camera, which I've seen listed at outrageous prices, then its probably worth holding out for the Yashinon.
This version of the yashica lens history is based upon what I've read, and examination of the camera's that I have. However it's in practise things are never that simple - I've seen 44a's for sale with Yashinon lenses, and LM's with Yashikor's. The factory probably used whatever was to hand to make whatever camera's were required. In addition there will be camera's that were repaired using an alternative lense - I'd not be surprised by anything, and I don't think its possible to fit everything together perfectly.
In the case of the Yashica's with the Copal SV shutter (everything except the 44a?), and even the Rollei there are 5 blades in the iris. This set up is also common on most modern camera's and results in the ugly pentagonal highlights you see in lens flare and out of focus bright points.
However the simpler Copal shutter with its top speed of only 1/300th has 10 blades making up its iris - the result being that its almost perfecty round. Any out of focus artifacts will show up as smooth circles rather than pentagons. As this applies most to the out of focus area's, its most obvious at wide appertues, when the Yashikor 3 is supposed to be performing poorly (stopped down it should perform well). Therefore wide open, the four element lenses might be sharper, but as the depth of field will be so shallow, the shoot will likely contain out of focus elements which may render more plesently on the 44a.
This is of course hypothosis based upon physical examination of the cameras. I hope to back it up with photographs some time soon. If you have any good images showing out of focus artifacts, then send them in, and we can investigate this further. It does sugguest that a 44a with a Yashinon lens could be something to look out for...