Here's an early Deep Purple song from the 1968 album Book of Taliesyn. Anthem was written by John Lord and Ron Evans and Lord uses it to exercise his leanings toward classical music with its baroque sound and use of both a mellotron and a string quartet. It also features Ron Evans as vocalist, the best vocalist Deep Purple ever had. http://youtu.be/TGW3jeZCFcQ
Then by 1971 they had kicked it up a few decibels and came up with Lazy from the album Machine Head. That organ and guitar still sound great and the new vocals work well in this song. http://youtu.be/dqM5L5JQseI
Machine head is their absolute highlight imo. And Ian Gillan their best vocalist The book of Taliesyn is very interesting but Machine head just sounds better and more pleasant. I'm not much of a progressive rock fan though, it's all about groove for me. Here's some later stuff, I prefer the instrumental part(s) https://www.youtube.com/watch?v=zzgzoqkZ33s https://www.youtube.com/watch?v=wYp5IcjvQRA
My Fave was always 'In Rock'. Seems like several lifetimes ago......................Have to agree with meagain that Ian Gillan was their best vocalist. He was Jesus too in the original recording of Jesus Christ Superstar. https://www.youtube.com/watch?v=XxNYOcNnmGI
Being old,,,I prefer the older Purple stuff. Jon Lord's organ work was ground breaking and established the early Purple sound. I'm not real excited by the songs you posted, a little boring for my taste. But that's just me. For example their cover of River Deep Mountain High was very good. http://youtu.be/lYDm69BXn8o
More with a prog rock flavour https://www.youtube.com/watch?v=GaakzEfCwUo https://www.youtube.com/watch?v=tXY1nF30PZo
He died in 2002. By then his music had mellowed somewhat. https://www.youtube.com/watch?v=Lhffry3GW9c
I often prefer the debut or first couple of albums of a band, but Deep Purple is an exception in that regard! Here's some stuff that can be called progressive rock that i do like a lot: https://www.youtube.com/watch?v=3h2WRTgLMeM