This is SteamPowers. One thing I appreciate is that I can set a user avatar, so of course, I'm Sailor Moon. You can check out the site via my referral link here (which just allows me to get some points for signing you up), or if you prefer here is a non-referral link.
SteamPowers also has a nice selection of other gift cards (although bear in mind many of these will be redeemable in the USA only), and pages of Steam cards and emoticons which you can alternately choose to exchange your points for. As far as the different pages/tabs in the "earn points" section of the site, I only pay attention to the default page featuring persona.ly surveys (as these are by far the smoothest and most enjoyable), and secondly to the Peanut Labs page (which I think is slightly more fiddly but still pretty nice). The other pages are full of spammy nonsense so I wouldn't recommend them. You can play about with it to see for yourself, of course, but those pages are the ones I prefer.
Some other sites:
For general surveys I use MySurvey (non-referral link) as I've found it's the most reliable, and for little bits of cash for occasional clicking, I use Qmee (referral link & non-referral link). They have recently started testing surveys too, but I recommend them because they feel slick and professional and it's easy to get a little bit of money from them without doing any surveys. You can also donate your Qmee earnings to charity if you so choose.
Hopefully some of this info is useful. I know a lot of survey and reward sites can feel quite erratic or confusing, so I really want to recommend the ones I feel comfortable with, and I love that there's a place I can specifically go to earn Steam Wallet credit.