I have my first acoustic -- a Japanese Epiphone bolt-neck steel string FT-145 bought new in the early '70s. Right now it has flatwounds and a Strat pickup installed in the soundhole. I keep it next to the computer and record demos with that guitar functioning for acoustic sounds, electric sounds (through amp modelers) and bass (through an octave pedal model).
My oldest guitar is a 12 string "vintage series" Ibanez englemann spruce/rosewood I got in 1972 after finishing college. Ibanez was a new brand carried by a small local shop back then, and it was the best sounding and playing 12 string I could afford at the time and I loved it. Unfortunately it had a truss rod failure and was shipped back to the factory in Japan for repair. Sadly, it seemed to have gotten lost in transit and we figured it was gone forever. I was elated when the shop called nearly a year later and said "guess what just showed up?" Yup - my Ibanez 12 string showed up at the shop with a new neck. Several years later I got away from playing and that guitar sat in a cheap chipboard case for almost 10 years with the strings at full tension. Strangely, the neck remained straight as an arrow! I still have it and play it occasionally. Doesn't sound like my Jumbo Taylor 355ce twelve, but still pretty decent though.
As for electrics, my oldest current guitar is a 1996 Fender Lone Star strat that I purchased when I got back into playing electrics. I had a mid 60's Fender strat and BF Super Reverb amp "back in the day" that I sold to finish college. Frankly, I have several USA strats now that are better than that one was and also have a mint 74 SF Super Reverb that's better than my old BFSR. Nostalgia is nice but old gear isn't necessarily better IME.
My '03 Gibson Historic LP '54 Custom. Such a great sounding/playing guitar, with the all mahogany body, ebony board, and A5 P-90 neck and std. P-90 bridge. A little weighty at 9.75 lbs., but I'll never part with it.
I have older guitars, but that's the one I've owned longest. Bought it new.
73 Tele custom-bought in 87; the neck is on it's last re-fret. The neck is within a hair of the end of it's adjustment. Funny, the only original part on it is the wood of the neck and the truss rod-everything else including the body has been replaced in the last 28 years