I have been using pennyful for the last one year and found that it is the number ONE site due to following reasons.
1) No minimum pay out.
2) best tracking of all cashback sites.
3) fast payment.
4) good cashback share.
In other sites the tracking system is not so good. even after tracking rejection rate is more. but in pennyful I didnt encounter any such issues.
KEEP IT UP PENNYFUL