Blackmore's favorite bands were Mountain and Vanilla Fudge? That's cool if he's being serious but you never know with that guy.
He's dead serious about that. He also likes Abba, Asia, Blondie, pre-Disco Bee Gees, Hendrix, Wishbone Ash, The Scorpions, Jethro Tull, Carmen and Neil Diamond! Anyhing with strong melodies or expression really. Vanilla Fudge were Deep Purple's role model early on and you can hear it on those first three Mk 1 albums very well.
And then Led Zeppelin II was released in October 69 and that changed DP's outlook on their music forever. About a year later - September 70 - they released In Rock which was totally removed from their Mk 1 output. In Rock was a conscious attempt to "outrock" Led Zep II, Blackmore wanted an album without any let-up, an aural onslaught from the beginning to the end. Of course, Led Zep refused the competition game and recorded the acoustic-laden Led Zep III as their next album. Had Zep III been another hard album, I doubt whether DP would have relaxed to be as experimental on Fireball (their album after In Rock) as they were. And after the experiments of Zep III and Fireball, both bands returned a bit to their roots and cut the experimentalism, crafting their respective commercial high points, namely Zep IV and Machine Head. The following albums, Houses of the Holy and Who Do We Think Are had them both branching out again.