'Ascension' has it moments of greatness but is not very focused or paced for many of the 40 or so minutes of chaos that insues!
I think 'Live at Birdland' is one of the Coltrane Quartet's most accessible(but still challenging) performances.
of course 'A Love supreme'
I also really dig 'Live at the Village Vanguard' mainly for the many takes of 'Chasin' the Train'(Some of Trane's best soloing).
Coltrane & Duke Ellington is also a very accessible and enjoyable album.(best version of 'In a Sentimental Mood' I've ever heard).
What's great about playing and listening to this type of music is that it challenges your mind and emotions at the same time. I take issue with the idea that Trane and Miles are lacking thoughtfullness. Have you ever heard 'Giant Steps' and looked at the transcribed solo? It's as about as intellectual as the theory of relativity! Not to mention the rest of Trane's "sheets of sound period"(ie. Blue Train or Monk & Coltrane) or the second Miles Davis Quintet for that matter.
The greats like Miles, Trane, Monk, Mingus, etc. were much more authentic and individualistic in their approach than alot of artsits today. They were speaking from their hearts and yes, their minds, not from a textbook like alot of the artists today. Alot of the jazz artists today are mechanical and lacking individuality, authenticism, and yes emotion. People like Wynton or Branford Marsalis sound completely generic and dated to me - they sound like they just read the 'how to be a musician' handbook
Take a listen to the Dave Holland Quintet for some modern and truly authentic and group oriented music.