So then i should go for....?
Nothing really. The gpu's fans are the most effective bottom intake fans.
-they are further away from the 'floor' and thus have more breathing room(won't have to work as hard) compared to fans you're thinking of placing down there
-they already draw air from the bottom, front the side, and the rear PCIe slots
Bottom intake fans don't do as much as you think they would, unless you're ok with the idea of running some at 1300rpm+ and making them the loudest parts in the PC...
And even then, they'd also potentially disrupt rear and side air intake, thus reducing cooling efficiency.
In this scenario I prefer high airflow fans to move as much air as possible to the GPU fan.
They typically have low static pressure, which makes them even weaker in the face of strong obstacles.
Great for exhausts, or front mesh intakes where HDD cages are optional.