As a long time player (little more than 20 years); and a player that has been frustrated for quite some time with the numbers of different discs out there; I have to point out that differences in plastic has been an issue since nearly day one. In the early days, the differences were in the discs themselves; i.e. early days saw cobras, stingrays, scorpians, whippets, etc. as the newest, bestest new mold. Then, the cyclone came out and changed the whole plastic world. These advances/changes were not hard to keep up with. Not long after this time; early 90s, you began to have to get the two new drivers and/or midranges released by each company, every year. Then, you had to find the correct weight range for your play. This was still doable, with minimal investment; especially if you knew a top player who knew your game and could help with this selection.
However, this is about the same time that Innova began blending their dx plastic with plastics similar to the discraft, cyclone type of plastic. Since then, the entire thing has blown up in a big way....the result being that each company (and add a number of companies or offshoots of the main companies; i.e. Millenium et all), now release quite a number of discs in all kind of speeds. They obviously also release many of them in three or more styles of plastic. Quality runs have always been somewhat of an issue. The situation now is that this applies to quite a number of other variables, placing one in a position to spend tremendous amounts of funds simply to find the disc one likes. By the time this is figured, the main run of the disc chosen may be already somewhat difficult to find.
The answer is as it always has been; and, that is, once you find one you love, buy five or more of them, and you are set for a season or two. Personally, I have been in limbo land for a couple of seasons now, as I am searching the my latest model. One of my main pro playing buddies, throws pro wraiths as his main fairway driver. I have given the wraith a good try for two seasons and doesn't seem to be the one for me. It's o.k. but no great love that is necessary. For him, it also happens to be pro wraiths that are king. This brings up another point, in that pro plastic needs to be replaced often.
To sum up this long post; man, I miss the days of simple choices in plastic!!! I do find it slightly encouraging that the old stand bys; i.e. rocs, leopards, valkyries, teebirds, etc. seem to be some of the still preferred discs.