The Podesta e-mails were far more damaging. For one thing, they caught Clinton saying that she had a "private position and a public position", which, as one questioner pointed out, amounted to being two-faced. She fumbled the answer to the question, and Trump got in a joke about her being not "honest Abe." They also caught Donna Brazile giving debate questions to Clinton, resulting in the former's resignation from CNN. Progressives were incensed over this--I called a Clinton volunteer list (people who'd given up an entire day to help her), this was the week before the election, and one guy told me he wished the Republicans had run Cruz because then he'd be supporting Cruz! Neera Tanden, a Clinton policy guru, couldn't even go on TV after her e-mails were released, in what she called "the worst professional experience of my life."
This Ken Vogel article describes the impact of the Podesta e-mails on Clinton's relationship to the left:
On the Fight for 15 and TPP:
On the progressive reaction:
http://www.politico.com/story/2016/10/wikileaks-hilary-clinton-progressives-230009
Imagine you're a jfern type, or even just a swing voter gauging Clinton's honesty on issues like the TPP, taking this in. And Trump mentioned wikileaks from his stump speeches. The impact was devastating. Had she not been running against Trump, such leaks would have caused her to lose in a Dukakis-style landslide, even without Comey.
Well, it was pretty obvious that Hillary was a liar when she made claims like Bernie being against the auto bailout during the debates. But for those not paying as much attention, yes I'm sure the Podesta e-mails did a fair amount of damage. I think it also convinced some Bernie people who were already angry at Hillary to switch from Stein to Trump. The Podesta e-mails did not change my vote, but I was probably a bit of a canary in the coal mine for liberal support of Hillary.
