As a Twitter user, I have accounts with both MyLikes and SponsoredTweets. I've been with both for a few months now, and here's how they stack up:
Paid to me via MyLikes since I joined in March, 2010: $9.63
Paid to me via PayPal since I joined in November, 2009: -0-, but with $20.19 pending.
SponsoredTweets has a $50 threshold before you even see a penny. This can be hard to reach if you have to set your rate low, which is something you definitely have to do to get advertisers to look at you on SponsoredTweets. When I first started, my rate was $1 a tweet. Not very many nibbles then, butI also had way less followers. A friend suggested I lower my rate to entice offers, which did come. However, my rate is still well below $1 and thus it is taking a long time to build up my account. Offers also don't come every day, though they do now have a list of CPCs that you can opt to tweet if desired.
By contrast, MyLikes has just a $2 payout threshold. If your account balance is greater than $2 on Friday, you receive a payment for whatever is in your account. This week I had a total of $5 and change and received PayPal late Friday night. I don't have to set a rate at MyLikes - it is CPC. If the Like is worth .22 per click, that's what I get. Of course, they do verify that these are legitimate clicks before crediting your account and thus there may be a slight delay (if you happen to be frantically checking the click stats on your HootSuite stats page.)
So based on payment, I give high marks to MyLikes. Provided you meet the payout threshold, you get your $2+ if it is in your account every Friday.
Will I be spamming my followers?
No. These messages are clearly marked as sponsored or ads. This means that your followers can choose to click or not. SponsoredTweet's opps, that is those that you receive offers for at your set rate, are fairly legitimate. The CPC's will require a little bit of research on your part to ensure whether they are spam or not. I've seen some that are misleading and those are the ones that I pass over. You can, however, tweet multiple opportunities out (paid and CPCs) so it is best to spread them out so you aren't Twitter bombing your status with ads.
With MyLikes, I am choosy about the Likes I choose to tweet. If I don't like the look of the company and think it is spammy, I don't tweet it. You can also post your Likes to your Facebook wall, but this isn't something I do since my Facebook is private and not related to my blog here. In addition, you can only tweet out one MyLikes opp per day. If you see two opps you are interested in, choose wisely because you get only one tweet sent from their site per day.
Will you spam your friends? Only if you make a concerted effort to do so.
Want to join either of these monetizing sites?
Below are referral links. Be aware that I would receive credit for referring you. With regard to MyLikes, they do have a contest going right now and I would earn an entry to win an iPad (plus I would also receive $4 per qualified referral who takes and tweets at least one MyLikes opp.) Granted, I have no delusions of grandeur here - other sites have far more marketing power to entice their readers to join. SponsoredTweets does offer me a referral bonus (10% of what a referral earns - so if you tweeted out a tweet worth .55, I would earn a nickel while you would earn .55). I currently have two referrals that have earned me a whole penny!