Microwave ferrite has much lower permeability and more conductive oxide filler.
<30MHz ferrite has the highest mu with cobalt doped iron oxide with much less conductive metal particles as beads around conducting wires. But high permeability and lower resistance SMD in a ferrrite power may use silver oxide with iron oxide and is more expensive.
But as you may have found there are thousands of variations in ferrite. with a dozen basic types.
The goal for load regulation is to have a high ratio of load to source impedance ratio, while the goal of ripple or spike rejection is just the oppositve with high series to shunt ratio.
You must balance cost with these variables for choices of impedance of ferrite , low ESR and high ripple current rating of Caps and low RdsOn FETs of switches to achieve low drop in LDO's and switches and reduce or eliminate heatsink costs, while achieving the desired noise levels.
You have the right approach using SMPS to LDO for noise. Magnetic costs in high density can be expensive compared to a large air coil and a few small ferrite beads or a torroidal coil with heavy gauge, but come down significantly in volume. More exotic materials are only worth the cost if the size is that important.
Also look at Toko, Murata and TDK. The best magnetics often come from Japan TW & Korean sources.