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.

quadro and Octo have 4 temp sensors inputs each so you have more than enough with just one controller. You could have one quadro with fan splitters, or all fans conected individually to an Octo already.

For the pumps, i can't speak for the D5 Next, i never used it
I personally prefer having everything connected to a single controller, so it keeps working in hardware mode from the one controller if aquasuite was to crash, but tbh, i never had that happen in 2 years using it, so it's a paranoid's concern :p

The D5 NEXT will have a temperature sensor embedded i think, but it may, or may not be useful depending on where the pump will be in the loop.

I have the D5 Next, which has both a temp sensor and flow meter.

I believe they're actually calculated based on certain other factors, but I also put two other dedicated temperature sensors at other points in my loop because I was certain it'd make a difference... All three readings have less than 0.1ºC variation between them, regardless of loads, which seemingly concurs with what people say about temperatures reaching an equilibrium throughout a loop.