Phoenix already has Open Door and Offer Pad doing this, as well as a bunch of smaller players.

I know there was a big rush to buy warehouse space.. not sure if you can make a profit selling it at 400 a lb.my thought was once it became more main stream the bigger players jump in and it goes all the way down to the price of tobacco.. why not ?

It also helps to build up a variety of team players for your future endeavors by checking out the company page here on Bigger Pockets to hook up with a few professionals in the area you need team support in.

In that time I've met more real estate investors than I can count, from single family to commercial, both small scale players and mega investors. 

I could probably setup and optimize lead generation funnels for acquiring various RE leads (eg. foreclosure leads) worldwide.

I realize you can get infinite ROI with BRRRR, but I don't think that's what the big players do.

Are these still the main players and if so, who would you recommend?

These company owners likely know what players would be interested in having a look.  

Has anyone been working for one of the large players and switched to KWC?

dont really knowand Blazers affect the real estate market like 0 %  .. other than the few players that buy maybe 5 or 6 multi million dollar homes..