Patti took the words out of my mouth ... there are as many opinions on thread as there are on what shoes are the most comfortable to wear. Not everyone is the same, not every machine is the same, and not everyone has easy access to the same thread.
This is the best I can suggest.
Choose perhaps 3-5 threads and purchase ONE spool of each of those threads in a commonly used color (medium grey, taupe). Use each of them and keep notes on such things as: were there any problem with breakage or shredding of the thread while using, note the amount of fuzz build up in all the usual areas of the machine (bobbin case, stitch plate, presser foot, and upper shank of needle bar), how does the thread look on your project (if used for quilting), note the needle and tension used, and was there any difference in your 1/4" seam width with the different threads (some 50wt thread is thicker than others).
What I like, and what another sewer likes ... may not be what you and you your machine like. YOU can be the only judge. There is NO right or wrong thread ... if you choose Coats and Clark over expensive Aurifil - that's what you choose.
Of course another factor could be what your LQS carries. NONE of the stores in my area carry my thread, I have to purchase it online. For that reason I purchased the color chart so I know what I'm buying.
I went through a similar experiment, but mine was far more costly as I bought a bunch of different colors of a specific thread before I tried it - and wound up HATING it and trading it all to another QB member. I have since found what is now *my* thread and for the most part I'm sticking to it - but I have purchased single spools of other threads to try them out.
Good luck with your experiments!!