It's not the same for Everyone. Sometimes you have a special place in your heart for your first. Sometimes you can keep your hands off that sexy littl number with the unbelivable cureves.
I'm talking about your Knife.
For me, it all goes back to my first Buck 110. Bought it as a scout back in, well, let's just say it was a long time ago. The thing's been through hell and back with me. Even though I absolutely love some of my newer knives like my Hinderer XM-18 with the Battle Black finish or the classic Sebenz 21, I still have a special place in my heart for that old buck with the brass bolsters.
I guess it all comes back to why you carry. For me it's a combination of need - and I do need a solid, reliable knife on a regular basis - and an extension of personality.