Rainbow was my first concert, as a 10th grader in 1983. Blackmore was amazing. I remember "Jealous Lover" lasting like 20 minutes, his fingers blazing the whole song.
I first got into Deep Purple about the same time, with "Deepest Purple." I went straight from there into the albums, with "Machine Head" being my favorite. I have the original quadraphonic mix on SACD...the mix is great, the sound quality so-so.