I wouldn't say that from 2007 - 2010 the #2 spot was occupied by the same person. If we look in 2007, Batista, Shawn Michaels and The Undertaker were all involved in the main events of WrestleMania 23 and remained in top spots throughout the year. Edge and Randy Orton began the short road to superstardom in 2007 also, so in 2007 it is hard to tell. In my own opinion, I would say Triple H. He returned at SummerSlam, so missed half the year, but was inserted into the main event, winning the WWE Championship and having feuds with Randy Orton and Umaga. Whilst Cena was out, Triple H was the guy. Batista is a close #2 as well, as he had that long feud with Undertaker.
In 2008, I would suggest that Triple H was #2 again. He was in the main event of WrestleMania XXIV representing Raw and was drafted to SmackDown as WWE Champion. He feuded with Edge, The Great Khali, Jeff Hardy and Vladimir Kozlov and reigned supreme on SmackDown for 210 days.
In 2009, Randy Orton takes the #2 spot. He feuded with Triple H and the McMahon family for the Road to WrestleMania, and Orton eventually won the WWE Championship at Backlash in April. He led the Legacy and feuded with John Cena over the summer and into the Fall. At this point, Orton had solidified himself as a full time main eventer.
In 2010, it is hard to tell because it was a year which featured a hell of a lot of guys trying to get the title. Other than Cena, you had Randy Orton, Sheamus, Batista, Edge,
Chris Jericho, Wade Barrett, CM Punk, Rey Mysterio, Kane, Jack Swagger and others I can't think of off the top of my head. I would say Randy Orton gets #2 this year as well because his popularity grew all the way from the Royal Rumble to Night of Champions, where his popularity was a reason why he won the WWE Championship.
So, between 2007 and 2010, Triple H gets 2007 and 2008, and Randy Orton gets 2009 and 2010. But, Orton has stuck around longer and done more to help his career, so I am going to say Randy Orton is the #2 overall in this four year period. Again, it is very hard to tell as this was a huge transition period. In 2007 we had tons of superstars who by 2010 had either retired or jumped ship and were main eventing TNA.