the LP I had around since I was a kid was Cheap Thrills by Big Brother so I was into acid rock and then metal but I was working with an older guy one summer when I was about 13 who argued that garage was better. I was successfully converted but not all at once - first he turned me on to higher quality rock than I was used to on the radio, cassettes of Sabbath, Johnny Winter, Motorhead, Deep Purple, Procol Harum, ZZ Top and obscure bands like Stray, Pink Fairies, Bloodrock, Bob Seger System. Then when I trusted his judgment some, he gave me cassettes containing:
Piper at the Gates of Dawn, the Easybeats, Mitch Ryder & Detroit Wheels, bubble gum, Mummies, MC5
That was that.
Eventually I got in bands and discovered WFMU, Norton Records, and got into music history, etc.
One tune that always jars me into astral time travel is "Uptight Tonight" by Flash + The Memphis Casuals [http://www.youtube.com/watch?v=fS38FDJffsk] but the haunting, plodding sincerity in "Truth Gotta Stand" by The Luv'd Ones makes me feel like every song I ever wrote is crass, hokey and a waste of everyone's time.