With regards to the Les Paul, Strat and Plexi...I suppose it was the realisation I was in this for "the long haul." I'd done the usual thing that guitar players do, "horse trading" equipment, buying and selling everything under the sun, you name it, at one point I had one! That "if only I had this I'd be great!" type thing.
It took me a few years but finally I realised it was all about you, the guitar and the amp. Not rack mounts, the latest "talent box", super-duper strings and picks made out of titanium from Mars. So I made an investment in gear that would last me until the end.
That said, the guitar I use the most is a Jackson Soloist. Very versatile.