1 and 2 are equivalent: only the specified route(s) are accepted. I try to stick with the 2nd method except for the handful of times I need to do something specific using the 3rd method (see last paragraph).
The third one is a little odd. The "accept" on the route-filter occurs first. What I'm trying to recall is what the fall-through behavior is for a route that doesn't match the route-filter. I only mix route-filter actions and term actions when one is set to reject and the other to accept. Since there is already an action applied to the router-filter I think the term's then action would apply to all other routes, which would result in all routes being accepted. Not 100% positive without setting it up, but about 90% sure that would be the behavior.
Basically, avoid the third method where you are mixing route-filter actions and term actions unless you are absolutely certain of what you are doing. I only do both if I need to pre-filter with the route-filter action and then have the term's action to do something else for all other routes.