Hi,
I'd highly recommend African Scenic Safaris. It is a small, family owned company based in Moshi. My friend and I chose to do an 11 day private safari with them this January, starting with three nights at Tarangire Safari Lodge and then camping at the Ngorongoro rim, in Serengeti and in the Lake Natron area. We knew beforehand the main places we wanted to go and Amanda was very helpful advising how to combine them into an itinerary. I had very high expectations on this safari, but it easily exceeded them all! Our guide, Thom, was amazing at finding wildlife and getting us the best possible vantage points. Our cook for the camping part of the trip, Omari, was great as well. I'd definitely recommend going for a private tour, since that gives you full control over how long you want to stay at each spot during the wildlife drives. As always when watching wildlife, patience tend to be rewarded.
Kind regards
Emma