I believe the President should have more power. Right now checks and balances prevent the President from becoming an outright dictator or a King, and the founding fathers intended to prevent this. Yet the President is still hampered by regulation at home on domestic issues. The President has little opportunity to affect change, and I believe this has held the US back as a country.
The constant gridlock, which is in part caused by partisanship (which was also intended), but also in part by the checks and balances, makes it difficult for the President to press for bills that could be positive for the United States. The US is one of the only countries in the world without maternity leave, as well as severely lacking a free healthcare system that exists throughout Europe, and this is along with numerous other areas where the US has been left behind. I would attribute this to the President not being able to meet the goals they set for themselves to be judged by. Obama could certainly have achieved much more if he wasn't constrained by Constitutional checks as well as by partisan politics.
Finally, like the other opinion shared, I would point out that even former Presidents acknowledge that they wanted to achieve a lot more. The fact it is generally established that of the three branches of government the President is the least powerful would lead me to suggest that it is these power constraints that have limited the President's to rarely achieving their political goals.