I had KelbyTraining for a year and enjoyed learning what I did there and learned a lot.
I've had Lynda off an on, usually for a year at a time, but sometimes just a month or two in order to learn something specific, for maybe 10 years, and have also enjoyed learning there, and learned a lot.
The difference for me was that I found the photography courses and tutorials on Kelby MUCH better than on Lynda, and found the Photoshop and other software courses on Lynda MUCH better than on Kelby.
From my point of view, the structured curriculum style courses on either/both are FAR more valuable than the shotgun approach of hunting and pecking your way through odds and ends on YouTube and other resources all over the net, mixing bad practices with good, when you don't know which is which yet, and not having a proper foundation to build upon.
It's just like in school, how you learn the alphabet before you learn to spell simple words, then you learn more difficult words, then still more difficult words, then you learn the proper way to put them together and use grammar and punctuation, then you write sentences, then you compose paragraphs, then chapters, and finally books. Each step is built upon the stuff you learned up until that point.
With the shotgun approach, mysteries and confusion and wasted time because of it are typically rampant. You jump in and click on a video to learn how to do something, but you don't have the proper foundation to know how to do the stuff that led up to it, nor why you should.
When you decide to build a house, you don't just start erecting walls and hanging curtains, then build a roof, then put a hole in it for a chimney, cut a few holes here and there for doors, then plaster and paint the walls, then realize you need frames for the doors, then realize you'll need water, sewer and electricity so you tear into the walls to install pipes and wires and have to repair the walls again, and THEN later when you think you're basically all done, try to put a concrete foundation under it all because the whole thing is starting to tilt like the leaning tower of Pisa.
Start at the bottom, at the base, at the foundation, and build your way up in a logical, structured, ordered manner if you want to learn something, correctly, efficiently and thoroughly. That goes for anything you want to learn, but it's especially true of more complicated things.