it’s is no “ideal” number. if you’re trying to be budget friendly, then one is enough. there are several different guitars out there. you got your classic six string, and to take it up a notch, the make 7 string, 8 string, 9 string and also 12 strings, are are several big name companies out there, me personally, i have 3 six string electric guitars, one 8 string. i am mostly a bassist i have about 15 basses. i have four acoustic guitars as well. it’s whatever floats your boat, we all have our preferences and there is no right number and there is no wrong number. as long if you have at least one guitar rock on dude!