i bought an ibanez mikro for my son. he's not even 3, and i have no idea if he's ever going to have the intention to play guitar, still, it's a fun instrument even for adults.
according to my luthier buddy, most short-scale guitars would do the trick, these are basically all the same regarding qc, usability and tuning/upgrade potential: squier mini strat, ibanez mikro, jackson minion series, esp/ltd junior, whatever. these are mostly made in china for their sub-$150 price, still, after a pro setup, a short scale guitar will offer acceptable tuning stability and nice tones. amp-wise, pick whatever you like, a roland cube, a yamaha thr or a line6 spider practice amp might be fine.
the attached pic shows the one i got for my kid (the guitar below is my 25,5" scale jackson slsmg for size comparison)
according to my luthier buddy, most short-scale guitars would do the trick, these are basically all the same regarding qc, usability and tuning/upgrade potential: squier mini strat, ibanez mikro, jackson minion series, esp/ltd junior, whatever. these are mostly made in china for their sub-$150 price, still, after a pro setup, a short scale guitar will offer acceptable tuning stability and nice tones. amp-wise, pick whatever you like, a roland cube, a yamaha thr or a line6 spider practice amp might be fine.
the attached pic shows the one i got for my kid (the guitar below is my 25,5" scale jackson slsmg for size comparison)

It's either Guitar or the Drums for him.
I am/was a piano player, so I would like him to try something different. If he gravitates towards the piano, then so be it.
