I think there's a case to be made both ways. Eisner certainly had more of a passion for the parks, but he's also responsible for opening two under-developed parks and will always be known for ruining Epcot in the 90's. Many people held onto some crazy belief that Epcot would return to what it was, which was never going to happen. Iger is just finishing what Eisner started in terms of Epcot, but at least the park will be a lot more fun than it was before.
Eisner added virtually nothing to the parks from 2000-2005, with Everest, Soarin' and Mission: Space being the only notables at WDW (and Soarin' was a clone from DCA with M:S being a project that took 4 years from demo to open) and nothing I can think of at DL Park. He also opened TWO MORE under-developed theme parks during these 5 years (DCA and HKDL) making it FOUR in total.
The beginning of Iger's tenure, from 2005-2009, was pretty weak. Besides Toy Story Mania (another DCA clone), I actually can't think of anything added to WDW outside of Seas with Nemo and Finding Nemo: The Musical. So all in all, the 2000's were an INCREDIBLY weak decade for both CEOs when it came to the parks. This decade has been much more active for Iger with DCA Expansion (to fix Eisner's wrongs), Star Tours 2.0, Test Track 2.0, Cars Land, New Fantasyland, Disneyland refurbs for 60th, Paint the Night (DL, HKDL), Soarin Around the World, Pandora, Toy Story Land, Star Wars: Galaxy's Edge, Runaway Railway, Beginning DCAs Marvel Land, Pixar Pier (I know...), Disney Springs redevelopment, Shanghai Disneyland, Hong Kong Disneyland expansions, Disneyland Paris expansions, etc. That's not even mentioning hotel development, new nighttime shows, etc.
Whether you like the stuff that's been added or replaced, you can't deny this has been a much more active decade, much in part to the pressure put on by Universal and Comcast's willingness to spend money, which has affected both WDW and DL in a positive way. I would say that it actually seems that Iger is finally seeing the value of investing in the theme parks, ironically just before he's leaving his position.