I was in your exact spot, many of the recommendations you have received are good. My advice is that you are a long way from picking an outfitter.
I'd start with what you want to hunt. Biggest question is plains game, dangerous game.
Then I'd focus on avail budget.
Then I'd focus on countries. For me, I knew I wanted to do plains game, so I started looking at SA and Namibia. I also knew I might just do it once so when I heard you could hunt plains game amongst the big five in Zim, I decided to go to the BVC or Save conservancies. Ended up having a great trip to the BVC.
I learned a lot of this info from online forums like the campfire and I also went to SCI which I highly recommend - and you will need at least two days - one to map it out, second to talk to folks.
If I was going back for PG - I would go Namibia, for DG I'd go Zim.
