Forza 4 is considered best Forza yet,and Forza 3 was quite weak,you literally mixing games for some reason,Forza 6 was very very good.I have no clue about what rubbish you talking,neither about what did they mess up,T10 clearly improving game,jump into eSport confirms that
If I was asked, I couldn't tell you the difference between Forza 3 and 4. I still have them both. I played them when they came out but not since. The fact that I barely remember Forza 4, makes me put it below 3 on the rankings. Forza 2 however, I remember very well. I spent ages doing custom paint jobs on cars.
Forza 6 is just far far too busy for my liking. It's over the top and needlessly so. All presentation. Voices telling me what to do and stuff. It drove me nuts. Like I said, I didn't even finish the demo, and if I were to pick my favourite type of game, driving would be right at the top behind the likes of Skyrim or Fallout.
Forza isn't the only game to (IMO) get worse as time's gone on. GT5 was also utter garbage. Terrible terrible UI. Terrible controls.
I think that peaked at GT3 for me. GT4 was more of the same, but far fewer F1 cars.
What I want from a driving game is this:
I want to load it up, start my career, pick a car. I want to be asked about my default options (driving line, manual gears, TC, ABS, stability etc) and then go. Never be bugged about it again. I want decent handling and that's it, other than a variety of cars.
you going to preorder the Xbox? Oh yeah, who doesn't? 
