Great Country. Very diverse with modern cities, to pristine, untouched by human, wilderness areas (Imfolozi Kwazulu-Natal)
There is desert, mountains, lakes, wetlands, beaches, wild bush, forests and open savanah
Every activity you could think of is available, birding, hiking, fishing, boating, bungey, surfing, diving etc.
It has a very good road infra-structure linking the whole country. There are a wide range of backpacker establishments through out as well as 5 star hotels depending on your tastes.
Best Part to visit - is a difficult Q to answer.
I have visited most parts of the country. It does depend on what you want to experience.
City life - clubs, casinos theatre etc - Johannesburg, Durban and Capetown.
Game Reserves (wild animals etc) - KwaZulu-Natal Hluhluwe, Imfolozi, Tembe, Ithala, pilansberg, Kruger park.
Desert - Kalahari
Mountains - Drakensberg mountains - Giants Castle, Didima.
Beaches - (diving/ fishing) Sodwana, Mphalane, Cape Vidal
Scenic Beauty - Captown, Garden Route
World Heritage sites - Drakensberg Mountains, St Lucia Wetlands, Cradle of Humankind, Table Mountain
Would you enjoy a visit to South Africa - sure you would, most people who have been love it with many visitors from Europe, UK, USA etc.