In my opinion there is no best destination.
Anywhere you go there are many things worthy to see and feel simply by visit.
I would recommend you:
Pemba or Beira as a starting point in Republic of Mozambique both have airports and both are major cities
Beira has population over 600 000 which makes me more comfortable, if I were about to choose.
Official language is: Portuguese, I am sure most of the Tourism and Hospitality staff speaks english.
Etherway, both cities will provide you with pleasant safari days. You could enjoy also the beach, Beira/Pemba city culture and enviroment. Night beach bars or quiet beach nights would be at your choice of hotel or bungalow.
I think, Beira International Airport is waiting for you.