Well purely looking at intervals I would say the pattern in each scale would be good to learning intervals (jumping from the root to any other given interval).
But when learning scales it is really easy to know BOTH! Why? Because if you know which note it is from the scale (for example the second) and you know which note it actually is ( for example an A, from the G Major Scale ). You can tell which chords belong in which key.
That works in the following way if you don't know that. (Using the G Major Scale here)
1st: Major ( In G Major Scale that chord would be G Major )
2nd: Minor ( In G Major Scale that chord would be A Minor )
3rd: Minor ( In G Major Scale that chord would be B Minor )
4th: Major ( In G Major Scale that chord would be C Major )
5th: Major ( In G Major Scale that chord would be D Major )
6th: Minor ( This is also the relative minor Key. In G Major Scale that chord would be E Minor ).
7th: Diminished ( In G Major Scale that chord would be F# Diminished )
8th or Octave, is the same where you start over.
Remember the pattern: Major, Minor,Minor,Major,Major,Minor,Diminished and finally the octave.
JJ