These two movies are barely comparable, other than they're both blockbuster smashes of summer aaaaaaand they're both based on icons of my childhood.

Transformers was designed and filmed to reach out to a broad audience. It was meant to be enjoyed by both adults and younger children (Both the older and newer fan base). The script of Transformers was absolutely awful, and it was the script that mainly gave it the appeal to the 13 year olds. Labeouf does suck, too. He nearly ruined Indiana Jones with his nonsense. :) So Transformers could have been a great adult movie, if it merely had an adult orientated script. The CGI in Transformers was pretty amazing  and I don't see it being matched by anything to date in the complexity of the actual transforming and the detail of the robots themselves along with their movement and interaction with environment. I'd have rather it have been a silent movie with action than listen to the crap characters were spewing out. They're jerks for being smarter to create the film for more people to enjoy than make the content intelligent. :(

Transformers lines annoyed me through-out the movie, especially the hiding-in-the-yard scene. Also Tyreise should be banned from being in any movie what-so-ever. Forever. 

Ironman was scripted for an older audience, and had a much better performance by a lead actor who was very well casted to fit the Tony Stark comic book fans are familiar with. Gwyneth Paltrow, however, is both unattractive and she performed horribly. Tarence Howard's girly voice is certainly not how I imagined the guy inside of War Machine to talk like, so that sucks a little too. 

Neither movie can be considered very smart, but Ironman is the more mature film of the two, even if it's still dumbed down. Can't hope for much more from a comic book movie. I think Iron Man is one of the best Marvel films to be produced. Though I have high hopes for the Wolverine movie. 

I think I'd go with Transformers for overall rewatch value since they're both just special effects orgies anyhow and Transformers had more action. Ironman was a more well done movie in terms of fitting the bill for what I was hoping to get out of it. I can't tell you how much I cringe at most every line in Transformers, as though not only it were meant for 13 year olds but it seemed as though 13 year olds even helped to write it. 

Most annoying part of ironman involved testing out his suit, a garage, fancy high priced cars, and the on-que resulting outcry the film producers expected from the bonehead fans in the audience. 

What'll be interesting is to see how the sequels to these films size up. It's assured now that they will be producing a Thor film, as well as an Avengers film after Ironman II is released, and Transformers is said to become at least a trilogy.