You had to put some poor langaab peasant Bantu kids to represent Kikuyus

Anyway, I know most Somalis here would definitely vote Somali as the most entrepreneurial people. But if we were to remove our tribe tinted glasses and assess the matter without bias, Igbos would be the clear front runners.
The Igbo tribe is more than 40 million strong in numbers. Of course they have a big business presence all over Nigeria, which is Africa's biggest economy. For context purposes, Nigeria's economy is four times bigger than that of Kenya. This goes to show the league in which the Igbos are playing in, in terms of business.
In addition, Igbos have a very large diaspora presence. They are all over the world. Any city you travel around the world and hear there is a Nigerian community around, chances are they are Igbo. These people are the real hustlers from Africa. There might be some bad apples among the Igbo people, notorious for Internet scams. But this doesn't take away from the Igbo entrepreneurial might.
As for the second and third spot between Somalis and Kikuyus, that is up for debate. Somalis most prominent business community is in Kenya but the Kikuyus have the edge in Kenya, by a large margin. The Kikuyus control the government, the resources and businesses opportunities. That being said, Somalis have the advantage of having a significant diaspora in several other African countries and in the west.