Methinks 'the best way' of loading one's assembly should depend on the nature of the code... You don't want to NETLOAD an assembly that hooks RibbonServices.RibbonPaletteSetCreated Event to fully initialize, as by the time you're able to enter NETLOAD that event has already come and gone.
There seems to be a lot of confusion about ribbon initialization. It's pretty simple, and you don't have to concern yourself with how/when your app is loaded.
If when your app is loaded, the ribbon exists, then you add a handler to the Application.Idle event, and the first time the event fires, you remove the Idle event handler so it doesn't fire again, and you initialize your ribbon components.
If upon loading of your app the ribbon doesn't exist, then you hook the RibbonPalleteSetCreated event. If/when that event fires, you add a handler to the Application.Idle event, and when that event fires, remove that handler from the Idle event and initialize your ribbon components.
So, in all cases, you are doing initialization in a handler for the Idle event, and the only question is when to add the Idle event handler, which depends on whether the ribbon exists when your app is loaded.
I haven't seen a case where that fails, including when the ribbon exists but is not visible. If there is some issue with the initializing your ribbon components when the ribbon isn't visible, I'd like to know about it, as that would seem to be the only possible gotcha in this case.