IMO “HSMAdvisor keeps getting better. Like the SFPF Calculator it now enables entry of the maximum acceptable cutting force in the “Machine Profile” settings” Cutting forces are usually the primary limiter of “hobbyist” CNC router performance. But HSMAdvisor also allows the entry (and/or download/upload) of spindle torque curves to predict when the spindle power would be the limiter. Millalyzer can do all of that and also show what those forces look like,
IMO, since cutting forces are reduced when spindle speeds and endmill diameters are increased as well as when chiploads are decreased, spindle speeds and endmill diameters should be maximized and chiploads minimized to the extent possible. But spindle speed should not exceed the endmill manufacturer’s limit for the material being cut. If the endmill manufacturer provides a minimum chipload for the workpiece, like Kennametal’s “Max Chip Thickness”, I’d use that. If not, @Julien’s recommended universal 0.001" chipload (actually IPT?) would be a good way to determine an appropriate starting feed rate.