Originally Posted by
[-Spiritus-]
Without parses, we really can't say what is "best" b/c we don't know your spell selection & eHPS over a bunch of fights.
Since that information isn't present, the best advice I can say is this. HST>MST for all spells other than PW:S. MST>HST for PW:S only. So, your ratio of HST to MST is entirely dependent on:
(1) Your efficiency and percentage of total damage resolved in using spells like PoH, GH, Penance, etc.
(2) Your efficiency and percentage of total damage resolved in using PW:S
If your efficiency on all heals other than PW:S is good, and they comprise a significant, majority chunk of your total damage resolved, then haste is for you.
If your efficiency on PW:S is good, and it comprises a significant, majority chunk of your total damage resolved, then mastery is for you.
The reason why so many Discs are haste heavy these days is you can squeeze out better throughput by having a mix of all spells other than PW:S as a significant, majority chunk of your total damage resolved, than leaning heavily on PW:S.