Completist here.
I started by buying each of the original 27 as they were released, then the 4 ComiCraft books and the lone Silver/black volume (Sub-Mariner).
When the re-Masterworks were launched, I sold my original 32 and started buying the new editions, first in the Marble versions. I say "first" because I eventually realized I preferred the Black/Silver method of numbering within a series vs. the marble method of consecutive numbering regardless of title. So I bought them all in the Silver/Black trade dress, and for a while I was buying 2 copies of each release, one variant and one silver/black. I kept the variants sealed, and read the s/b release.
I soon realized the insanity of this, and sold my variant run for a nice sum (I believe I had purchased the first 58 or so volumes in this form).
I have all the s/b releases to date. I also have a complete run of DC Archives - I never intended to buy all the Archives, but when the original Masterwork program stalled I needed something to throw my money away on !