OK, I will give you the things as I see them, but I know you will not agree with me, but here goes:
Firstly, I have watched F1 since about 1994, so that's as far as I will comment.
1996-1999: Clearly Schumacher was number 1. Remember, for instance, Suzuka 1997 where Eddie Irvine's car was risked by running a much higher engine range, and he qualified way ahead of everyone else, and he slowed the Williams cars down all race long? I remember there were many instances where Irvine gave position to Schumacher during these 4 years.
1999 was also infamous for Irvine claiming that Ferrari didn't want him to win their first driver title in many years as they saw Schumacher as the one who deserved it.
2000-2005: Barrichello. Multiple times. Barrichello was forced to yield on the last few laps many times. Austria 2002 comes to mind, many others that do not come to mind at the moment. 2005 was so crap that nobody even knew whether they had a number 2, never mind number one - due to the car mostly.
2006: Massa was clearly number 2, not so much on-track, but clearly everything was geared toward Schumacher winning, as shown by the clear quali and race gaps in majority of races.
2007: was very open till very end, when Kimi was assigned number one. IIRC Massa led the almost whole Brazilian GP, only to yield to Kimi for him to take the title.
2008: Kimi-Massa were very even until about Spa where Kimi spun, and it was clear that - besides mathematically - Massa had a much better chance to succeed.
2009: Very close year again in standings between the 2 up til Hungary, with Kimi clearly number one after - did they have any other choice with Badoer there? Fisichella clearly wasn't up to it either.
2010: Up to Germany it was relatively even between the 2, until 'Felipe, Fernando is clearly faster than you'. The rest is history.
2011-2012: Clearly a continuation of 2010, with Massa every time being the Guinea pig in terms of tyre testing in variable conditions, having to sacrifice his races.
That's all I could think of off the top of my head, but there might be more proof to find
For the record, I've always been a Schumacher fan, but it would take a blind man not to have seen the obvious bias toward him at both Ferrari and Benetton.
That's my opinion, and you ain't changing it. Thanks for listening.