What I'd say is that lifting median incomes is a really, really hard task. You can focus on closing the gap between average and the median by promoting more equality, though that won't work with a Republican Congress (and it's a hard task even if you can do whatever you want). You can try to aggressively promote full employment (meaning first appointing a Fed chair willing to let unemployment fall and then fiscal stimulus if necessary--but that's impossible with a Republican Congress). You can also try to focus on increasing overall growth, through infrastructure and R&D investments (Republicans have expressed willingness to go along with that in principle, though they've blocked actual attempts). Allowing more immigration would help there (though, you know--also, I think some people genuinely think that it would have the opposite effect). I wouldn't expect those things to be a magic bullet that dramatically raises living standards for the median American even if they could pass, though. I'd think expecting all that to lead to a one-time 10% boost would be realistic though a little optimistic.
That's all just looking at the economy. I think the peace of mind that comes from at least near-universal healthcare is big for everyone, and climate change is, to me, probably the single most important quality of life political issue.
The results aren't always the same, and they'll continue to be different going forward. Though, as you can see, Congress really matters. Obama was able to do so much because he had a Congress that agreed with him on a lot in his first term, and conversely, Trump or Rubio will be able to do a lot of what they want if they win. If Clinton wins, she will probably provide most of her value (from my perspective, at least) in vetoing crazy bills.