Personally for me, i'm a rather big fan of Tamers to an extent, as well as Adventure and 02 (I will admit i have not finished all Digimon series, i got half way though frontier and half way through Fusion, but the rest i have yet to watch. I have seen Tri though, can't wait for the next movie!)
I say that after tamers, the only note worthy season is Savers/Data squad though it's just my opinion.
As for a reason for Digimon coming to the Real World, i was thinking that a Virus of some sort infected the Digital World, and in an last effort, the Digital World ejected as many Digimon as it could into the Real World before the Virus could get to them.
Ok, that sounds about right. I'm not going to pick by that anyway but I'd guess the Vaccine attribute would help.
I've Been thinking of what line I'd use (it'd probably be repetitive to use the Keramon or Mugendramon line) and it's still hard to come up with anything. One thin that drew my eye though was
Aegisdramon
but I think
Its Special Move "Shine Breaker", in which it simultaneously fires concentrated bombardments of shining energy and bombardments of scorching energy at the target, from all the cannons on its body, completely annihilates the target with the gigantic explosion of super-destructive energy produced from the fusion of the two types of energy at the point of convergence of all the bombardments.Sounds overkill
I think it's back to Square 1: Find a Digimon
Edit: After Brainstorming (Found that Cannondramon again) I'm pretty much set on what a good (enough) line would be down to the Child/Rookie. Elecmon or Patamon, Centarumon, Assaultmon, Cannondramon (Pics in hider)