I add what I am about to add from a personal perspective of what works for me ....
Last weekend I rode a route around Long Mynd. Its an annual ride that Ive ridden for the last three years.
This year I rode the route on a 26'' wheeled bike, the last two years were 29ers.
Two observations .....
1) I felt more confident riding the 29ers from the perspective of rolling and technical "bits". I found that I was much more aware of what I was doing on the 26'' wheeled bike and more conscious of my decisions.
I found (and find) that less work goes into my riding of 29ers and (for me) its more enjoyable than the same ride on a 26''.
2) Despite having more gears and suspension on my 26'' bike the 29er was faster. I appreciate that this is hugely subjective so I will just park that now