How many types of sewing machine needles are there???

I used to buy the Dritz Universal needles and use them for sewing any type of fabric.  But that was before I discovered my love of silks and knits.  Then I bought Dritz ballpoint needles.  Great for knits but I was still looking for something more appropriate for my silks.  Then I bought Schmetz Microtex.  Perfect!  But why are they so much more expensive than Dritz?  Now I found Organ and Klasse needles online.  And now I'm confused. 

I understand that certain fabrics need certain types of needles.  You should also buy needles based on the weight of the fabric.  Got that too but what's with all the different brands of needles?  Is any one really better than the other?  I have Singer sewing machines.  I know I don't need to buy the Singer branded needles but I don't know that the Schmetz I've been buying are any better than the Dritz.  The Schmetz packaging is certainly nicer than the Dritz and more expensive...so they are better, right?  Ugh....

I've searched high and low and it seems like it's a matter of what will work on your machine and what you like better.  There doesn't seem to be a clear consensus except that Organ is cheaper with good quality, Schmetz is more expensive but easier to find, and everything else is a toss up.  For instance, I still have a few Singer branded needles that came with my CG-590.  The "denim" needle supplied with the machine works well and fits perfectly.  The Schmetz "denim" needle won't even fit into the needle clamp...but it fits my Singer Esteem just fine and works great.  So I guess you are just S.O.L. if you buy a needle that should fit and doesn't. 

If anyone wants to sound off on this, please do because I'm lost.  In the meantime, I guess I'll stick to my plan to buy Schmetz when they are 50% off at Hancock's and JoAnn's or buy Organ/Schmetz in bulk online.  Why not buy the Dritz?  The packaging just isn't as pretty.  Weird, I know.

During my internet search, I did find several good references about sewing machine needles and even some good sources for bulk supplies.  Enjoy!

• For the history buffs...History of the Sewing Machine at the Museum of American Heritage
• Threads magazine articles:  Sewing Machine Needles--An Overview and Machine-Needle Know-How
• Every possible Schmetz needle described: Schmetz ABC Pocket Guide
• Description of Organ needle types by Diamond Needle Corp: Organ Needles
• Stores selling needles in bulk (in no particular order):
• AllBrands.com
• Schmetz (more expensive but better selection)
• Discount Embroidery Supply (can order less than 100 of each type)
• CTS USA
• Atlanta Thread & Supply Company