OP I'll try to explain as best I can as a guy who has voted democrat his entire life:
Hillary does not seem genuine to me. She comes off like a character on House of Cards. She changes her stances on issues that are very important to me and has dragged her feet before finally picking a side on others.
Some examples:
-Trans Pacific Partnership
She changed her stance on this. She once called it the "gold standard" for trade agreements and now has since turned 180 and no longer supports it. Bernie has been on the right side of this one since it started to leak to the public.
-Gay Marraige
She was against it and vocal enough about it as late as 2007. Now she is in favor of it, but I think public opinion is largely in favor and that is why she started changing her tune in 2013. It makes me think she changed her stance because it was the popular one to take.
-Keystone XL
She took a very long time to come out against it. Meanwhile, Bernie was there seemingly on day one calling it garbage.
-Net Neutrality
Clinton supported net neutrality since 2006 which is great. I actually really appreciate this about her. However, Bernie was very vocal about it during the times when it came under fire the most. This is actually what put Bernie on my radar, several years ago. I was in school writing papers on it and was introduced to "The Bernie Buzz" newsletter where he was rallying people to defend net neutrality. I also started seeing him on Real Time with Bill Maher about then or shortly after it feels. While the candidates are probably pretty even here and Clinton has put in work just as Bernie has, Bernie was the loudest at the time when I was paying most attention.
-Gun Control
I don't trust Hillary to protect my 2nd amendment rights if she believes it will benefit her to let them dissolve. I think Bernie has a better understanding and respect of what gun rights mean to different people across the country and I believe Hillary doesn't really care one way or the other.
-Health Care
Clinton seems to be backing off of universal healthcare in recent days. I'm not sure where she will end up with this, but I like Bernie's stance that it should be a right of all people to get health care. I don't see him changing his stance on that and for that reason, that's another point for Bernie.
-Money in Politics
Hillary takes money from Wall St and big corporations. She has a Super PAC. Bernie does not. If you need an example of why this is a problem, look at how dysfunctional the GOP has become as they struggle to felate their corporate masters while their base turns on them. Even Obama serves corporate masters and if you doubt that, the TPP should be the example to demonstrate that point. I think back in 2000 it was laid bare that our elections aren't really ours. That really bothers me and I see Bernie as somebody to fight that machine.
Its just hard to get excited about somebody that I don't think feels strongly about her policies and will change her stances when it seems like she might gain political leverage. I think she's a game player and in our current world of politics, that's just the nature of the beast. I think for a long time, you would HAVE to be a game player to get by in our political structure. However, Bernie is talking about changing all that. I know he can't do it by himself, but I am excited at the thought of him ushering in a new age where politics aren't so shady and corrupt. I want big money out and I think he's the one to lead the charge.