SurveySavvy has some very nice rewards, but they can be few and far between. Even when you get a survey, they are very hard to qualify for. The plus side is they usually pay very well. All the rewards are paid out as a check that is mailed to your home. I usually wait until I have at least $25 in my account to cash it. One nice thing is that you can refer other people to the site, and get rewards from when they complete surveys. I've never really used this feature, but it could generate a nice income if you have a lot of friends that are willing to take surveys.
SurveySpot has been mostly miss for me lately, I've found it very hard to complete a survey and get any points. Each survey is typically worth 75 points (which translates to $.75 cash) The rewards can be paid out in Gift Cards or Paypal. I personally like Paypal. I can pay for things like Netflix and never have to worry about spending any real money on it. The nice thing about SurveySpot is that if you have time to kill, you can click on a link to take multiple surveys in day.
I've used Toluna for a long time now, and recently I feel like it has gotten a lot better. The surveys pay out less in points, but they seem to be easier to qualify for. Surveys vary from anywhere from 1,000 points to 3,000 points. 3,000 points seems to equal about $1.00. I like Toluna because of the sheer number of rewards. You can get gift cards to Sears, Walmart, they will mail you a check, they will pay you in Paypal. You can even get merchandise from the site.
Harris Poll has one very nice pro. Whether you qualify for a survey or not, you will almost always get 15 points. Every 125 point is worth $1. So every ten days, just for clicking on a link and answering a few questions you could potentially make $1.00. Not bad for not doing much. Most surveys are worth between 50 and 125 points. The only payment methods I've ever used were the gift cards. They can be slow to arrive, even though they are all digital. No worries though, I've always gotten my gift cards. One thing that they do every once in while is send out special community invite surveys. If selected for the community, you take at least 4 short surveys every month, and they reward you with a $10 Amazon gift card.