If we are talking in transference to oly lifts then both are important. I don't waste my time doing deadlifts, I just do pulls. In terms, of replicating the bar path of a snatch or clean, it is challenging.
Snatch Pull - due to this being generally a lighter weight than clean pull, this has a tendency to be used more from experience. I personally struggle with retraction and posture with this lift as its normally at 100%+.
Clean Pull - Due to it being a considerable weight (100%+ of clean), this weight tests my first pull and postural control. Anything over 3 reps normally turns into a clean deadlift.
If we are talking transfer into athletic performance, It really depends on the athlete and their ability. Normally less experienced athletes would use the blocks, as the 1st Pull/start position adds problems later in the lift and they get the appropiate adaptations from the 2nd Pull/Drive phase.
In my current program, I am using more snatch pulls than clean pulls as I have more issues with my snatch than CJ. I guess what I'm trying to say that it all comes down to speification. The snatch is always taught first by most coaches, so that may be a hint to which has more transference to oly lifting in general.
GO HARD OR GO HOME