(Edit: I originally wrote this reply while suffering from an eye migraine and was, barely, able to see the screen. Hopefully, it is cleaned up.)
I have not as as of yet run 5e. However, when and if I do, I plan to include a lot of third party material just as I did with 3e. I currently have several sub-classes, a few classes, and several rules variants that I plan to use as well while other concepts can be handled via I am a banana's 2e kit conversons. This assumes that I just don't port certain ideas from 5e back to my house ruled 3e.
The goal of my using third party sub-classes and classes is to provide additional options that fit my style and campaign since I was disappointed with several sub-classes and one entire class in the PHB and nearly every subclass in both the SCAG and XGtE. From the PHB, I will not be used using the Totem Barbarian, Circle of the Beast Druid, the Monk class, and the Sorcerer archetypes (I will, however, be keeping the Sorcerer and using at least one third party subclass). I am also debating about allowing the Eldritch Knight and Arcane Trickster archetypes (the former is, probably, being replaced by a third party class and, if I can find a base class for the latter, it will also be replaced) . Similarly, all but one or two sub-classes from both the SCAG and XGtE combined will be allowed (if I decide to allow them rather than something similar from a third party). The remaining sub-classes from those supplements either a) don't impress me conceptually; b) don't impress mechanically; or c) I have found a third party class or sub-class that, in my opinion, handles a given concept in a manner that I prefer to the official version.
As for some of the specific third party options that I like, several can be found is a previous thread that I had started. My original list excluding DMs Guild and RPGNow/DrivethruRPG stuff
here
and a follow-up post
here. The list is not complete.
For websites and blogs where I find or have found interesting things, you can check out this
post from a thread I started on websites and blogs (note: a few sites have not been updated in some time). Here is a followup post in the same
thread. Again, the list is not complete. For instance, I think that I recall Sterling Vermin not being on the list.
I'll post specific items companies and/or authors from RPGNow and DriveTrhru RPGl later.