Compared to new tech and i' going to say bikes from the last 3-5 yrs, IMO nothing on a 20yr old AC1 is relevant or worth keeping
modern Geo with longer WB/ shorter stems/ steeper seat posts/ slacker head tubes/ tubeless 29/ 1x/ longer WAY better travel/ dropper posts/ carbon frames is all the new stuff
unless you are lucky enough to find a 3yr old garage queen if you get something too old besides the geo being all wrong the parts will be worn out
I see alot of new entry level FS Giant hereabouts probably cuz we got a giant dealer in town and cheap price
there is alwasy someone older than you out thar