These are the best PTC sites, atleast for me. Because I got paid by them.
Neobux is a instant payment site. You will be get paid after reaching the $2.
Buxout is a instant payment site. You will be get paid after reaching the $5.
Sandraclicks is a instant payment site. You will be get paid after reaching the $5.
Though it was not a instant payment site, they will pay you in a week. Minimum payout is as low as $1.
These are the other sites that I got paid by them.
This the a good site that pays for only running the software in background. Even the earnings are less, but it was good to have because it was free money.
GPtreasure is a small tiny program that gives you money from completeing offers. Every offers is about just registering to another sites. Payout will be through paypal after confirmation on every friday. No minimum payout. Earn the cash directly to your paypal account. Eventhough the amounts are small, but it is nice to have.

I was also interested in these sites but I am trying to reach my minimum payout.
Take the globe was trusted by many members as I do. You can try it if you want. I am trying to reach the payout. It has the plenty of adds daily. Minimum payout is $10.