You still need fans for airflow. Considering these fans are $15 new you can get much better fans based on much newer proven designs like this Corsair SP120.They may be, however I've been using four for at least 10 years no problems.
Of course they have been run at a much slower speed than their max speed and they do so well with a radiator.
However I would love to use only what fans are necessary as I really do not like fans and much prefer liquid cooling whatever possible.
If you get a 360 AIO you'll need at least 3 for that radiator, 1 in the back, and I'd put 3 on the bottom too.
The computer itself comes with fans that work fine and can get rather silent. Buying more fans will add at least an addition 100 to the cost.