I would say its toss up between the 8400 and the custron. The custron will not require a mounting kit, and will have OEM looking buttons, which is huge in my opinion. Schoche/Metra mounting kits, needed for the pioneers, suck, but they are the best we have.
Personally, I got a 3400, and quickly upgraded to an 8400. I never touched the 4400, but I REALLY like the 8400. It really looks nice. If you go to amazon, the price diff is a bit over $100, which is significant, but totally worth it IMO over the 4400. The screen looks nice. It was easy to wire up, and I am happy with it, despite