I had one of my transaction stuck for quite long time. I tried some free bitcoin accelerators but it had no impact on the speed the transaction. Later the transaction got confirmed on its own. So I feel that these free BTC accelerators are just marketing gimmick to sell their paid options or to drive traffic on their sites. Do you agree with this ?
When your transaction is in stuck, your best bet is to use a legitimate transaction accelerator that includes your transaction in a mined block or contact a person who has access to mining pools and can include it. Your another option is to not use fake transaction accelerators (they only broadcast transactions), just do nothing and hope that nodes will forget your transaction and you'll be able to resend them again.
Most of the time you should be able to use Replace by fee or Child Pays For Parent option.
Hugeblack gave you a good list of real transaction accelerators, I'll quote his post.