for silent builds you should look at putting as many rads as your case can support (to an extent).
the 360 should be enough for a 3070, and the 5600x barely puts out any heat
but the more heat exchange surface you have, the slower you'll be able to run your fans.
How many fans will you have?
Quadro and Octo are pretty sturdy, you can use wire splitters as long as you don't exceed the max power draw. From your description, it seems fine to use either of those. And since you don't need individual control over fans on the same rad, you should really use just one output for the 3 fans on the 360mm rad. But nothing wrong in having them all in discrete outputs, tied to the same fan curve.
So, Quadro can do the job, Octo will leave you more headroom and one additional RGB channel
Aquaero, can't say, never tried it
but with water temp, and flow sensors, that's about all you need to monitor and get everything out of a cooling loop. It has hardware virtual sensors so that could be a big reason to get it.
It can run completely autonomously from Aquasuite.
Octo and Quadro need Aquasuite to run the virtual sensors, but can run autonomously directly off the sensors connected to them.
An example is if you want your fans to react to the difference between ambient temp and water temp (which is a virtual sensor), Aquaero can do it without aquasuite in the background. Octo/Quadro need Aquasuite.
If you only run the fans from water temperature (no calculations needed to get the control variable), both types of controllers can do it without Aquasuite.