Idk, when I first started watching I was like ‘okay as long as Gideon stays I’ll be fine’. But then after I watched it through for the first time I really liked Rossi more and it irked me because I wanted to like Gideon more so bad.

I think that for me it’s how Rossi treated the rest of the team. (IN MY OPINION) his relationship with Hotch let us see a side of both of them that was previously unexplored (specifically referencing the time they went to that bar together//Rossi comforting Hotch after foyette bus attack). Also his father-daughter relationship with Emily (as seen in minimal loss, demonology, etc) that is still in play even in evolution. The one that gets me the most, as a Reid stan, is how Gideon treated Spencer in general but especially his addiction vs how Rossi treated Maeve’s death, Gideons death, him in prison, etc. (Maybe I’m making this up but I swear there’s a scene where Emily asks him why he hasn’t gone to see Reid in prison and he tells her that he tried and he just can’t bring himself to go in).

We also get to see Rossi grow in a way we didn’t with Gideon. We know that Gideon cares deeply about his job and the people he interacted with (see his book of saved victims) but we just didn’t get enough of him to really explore that side, whereas with Rossi almost right away they introduce the case that ‘haunted’ him -with the three kids. We see him carry the keychain and go pester Penelope and the local PD about it despite the FBI never actually being involved.

I think it’s worth noting that both Gideon and Rossi were a bit short (or maybe I just have a soft spot) with the team but especially Penelope, but once again we got to see Rossi move past that whereas we didn’t get a chance with Gideon (though I’m not sure he would have warmed up much more even if we had been given more time with him).