From my (limited) experience, it seems like the Reserves are a bit less selective than Guard Units, but I would like to end up eventually at a Guard Unit. I just am trying to weigh out if the best option is if selected for the Reserve slot to take that and hope to transfer to a closer Guard unit later, or wait and Apply to more Guard units and hope things work out.
Also with the Reserves, route to OTS and UPT is much much quicker, whereas the Units I'm looking at are a year or two down the line.