I've actually started trying to get back into it just this month so I can point you towards a few places. Most of the bigger publishers have their own proprietary apps on android/iOS. Comixology is technically still around but it's really just a bad wrapper skin for Kindle as far as I can tell.

The desecration of Comixology has pushed me really heavily towards finding stuff that will give me an actual file without DRM so that I can still have my comic once all the servers go dark. So far I've found that DriveThruComics and HumbleBundle are the best places to go to for that, although the selection is limited at the moment.

There's a couple apps in the wings looking to fill the space left in the market by Comixology's implosion. GlobalComix looks to be on the right track with getting a lot of publishers on board and offering some DRM free options while also being creator friendly, but their app is not remotely ready for prime time and as a result I've not given them any of my money yet. The other player in the same sphere is Omnibus but they're iOS only at the moment so I've got no idea what they've got going on.

If you go the DRM free route, I'd suggest dropping the $6 for the CDisplayEx app. It's an excellent comic reader and does a decent job of tracking read and unread stuff. It's not as good as the old pre-Amazon Comixology, but it's as close as I'd expect to get from a standalone reader app. Worth the money in my opinion.