Back in the 1980's, when dinosaurs walked the face of the earth, Popular Photography used to do camera and lens testing on 35mm equipment. If I remember their results correctly, the 50mm f1.8 was given a better score than the 50mm f1.4. These tests were generally based on sharpness, distortion and contrast. I certainly cannot argue with the general reputation of the 50mm f1.8 being a fine performer, but for my uses, the 50mm f1.4 is also a fine performer. I will try and give you some of my personal observations.
Zuiko 50mm f1.8 Auto-S
Olympus made a lot of these. They were cheap to produce. Optical construction is six elements in four groups. This lens went through a series of revisions and there are probably five different versions. On their earliest lenses, Olympus used a thin silver accent at the front of the aperture ring and at the front of the filter threads. These are called Silvernose. Earlier versions were single coated and later versions are multi-coated. The single coated versions were labeled F.Zuiko (there are six elements and 'F' is the sixth letter of the alphabet). The last revision has the following markings on the front of the lens: "OLYMPUS OM-SYSTEM ZUIKO AUTO-S 50mm 1:1,8 made in Japan". Filter size is 49mm.
The 50mm f 1.8 Zuiko has the reputation of sharpness and very low distortion. I have four of these at present ranging from a silvernose F.Zuiko to a "made in Japan" with serial #3632896. I don't use the 50mm f1.8 Zuiko all that much, but when I do, it always makes a sharp and contrasty image, if I do my part. At f1.8, these are quite sharp.
Zuiko 50mm f1.4 Auto-S
The 50mm f1.4 Zuiko went through at least four revisions. Optical construction is seven elements in six groups. Filter size is 49mm.
This lens is the red haired step-child of the Zuikos. The camera magazines that you mentioned earlier found a distortion and contrast problem with their test lens, and the 50mm f1.4 has never shaken the reputation of being a dud. I own three 50mm f1.4 Zuikos. I have a Silvernose G.Zuiko and and two of the last revision. I have two bodies that always have a 50mm f1.4 mounted. These can be a little soft wide open but I have no problems with distortion or contrast. I cannot help but think that the lens testers got a miss-alligned lens to test. The highest serial number that I have seen is 1153xxx. If you can judge by serial numbers, Olympus sold well over one million copies of this lens and sales of this lens was roughly one copy for every three or four of the 50mm f1.8. This lens originally sold for roughly 175% of the price of the 50mm f1.8, so my take on this lens is that buyers did not shun the 50mm f 1.4.
G.Zuiko 55mm f1.2 Auto-S
I have two copies of the 55mm f1.2, one is a silvernose and the other is all black. Both are single coated. As far as I can tell, this lens was discontinued around 1981 when Olympus went to multi-coating on all lenses and it was replaced by the 50mm f1.2 Zuiko. These can be soft wide open and the depth of field is quite shallow. It can be difficult to accurately focus wide open in low light especially when the subject is close to the camera. The up-side is that you get a full stop more light than the 50mm f1.8. I don't own nor have I ever handled a 50mm f1.2 Zuiko. These take 55mm filters.
Zuiko 50mm f2.0 Auto-Macro
This lens replaced the 50mm f 3.5 Macro and it employs a complex optical formula of nine elements in seven groups and it has floating element design to focus down to 1/2 life size. Filter size is 55mm. If you are into pure distortion free performance, buy one of these. You will have to pay a premium for the performance.
I have a couple of comments to make before I am done. I always use a lens hood. The benefits are better contrast and reduced lens flair. The best money that you can spend is to get and use a lens hood. I would also suggest that if the 50mm focal length is for you, get several different copies of lenses that interest you and keep the 'best' ones.