The t-45 Goshawk is about as close to the T.1 as the F-16A Blk 10 is to the F-16 Blk 60.  Entirely different air frames, systems, performance, etc.  Now that being said, having to learn how to do massive systems management in the combat environment, then the A-10C is the best place to start.  If your looking for something that will let you click around the cockpit with some basic systems and a lot of go-fast, then the F-5E is for you.  The Mirage is just well.....French.  I would start with the A-10C though if you haven't bought a DCS study level module yet.  Its the most seasoned of all of them to-date.  There is a lot of content out on YouTube, these forums, etc.  But the reality is there is no 1:1 for the Hornet.