In light of recent events regarding Comixology, I'm personally about to focus more on purchasing comics through DriveThruComics instead of Comixology.
Here's the factors and resons behind my choice.
1. I already have DCUniverse for reading DC Comics. I could get Marvel Unlimited at any time, as well.
I also can read comics for free through my library with Hoopla.
2. I've long used DriveThruRPG, DriveThruComics parent site, for my digital rpg purchases. And I've never had a problem with them.
3. Comics purchased through DriveThruComics are downloadable. Most often in pdf format. So you can file them away on your computer or a disk drive. Safe and secure.
4. For the publishers: Purchases are watermarked with the user's name and order number. This deters piracy somewhat.
5. Their site is the most 'mainstream' outlet I've found. And the most current.
Others considered were IndyPlanet (not as current, limited in content), Itch (caters mostly to NSFW audiences) and Webtoons (if you only like manga stuff).
6. Some noted publishers already use it: Caliber, Heroic, Top Cow, Dynamite, Valiant...
7. No 'one-click' bs. We use one Amazon account here in our house, and have a few different cards tied to it. 'One-Click' bypasses the cart and the card selecting, using whichever card was last used. I had to cancel an order once because I accidentally charged another card for an impulse buy of a book. With DriveThruRPG, I'll never have to worry about that again.
8. All the creators are credited on the store pages.
Only downside I see is that Rebellion stopped using DTComics at the end of last year. So for 2000 AD and Judge Dredd, you'd have to use their own website. But as they sell pdfs there, also, that's not a big deal. They'll mix as normal in your computer's folders.
Btw, the Deal of the Day today on DriveThruComics is Strange Detective Mysteries, marked down from $8 to $4.