Personally I am a bit afraid of BTC mixers. Anything can happen and ruin the whole transaction.
I will tell you my personal case of mixing. I would not say that is the best or that I recommend, take it just as a real example.
Why not try to tell your experience in mixing so that we are going to know if that is going to give us a lesson or not but still sharing that here is going to give us additional knowledge here.
Bitmixer. They're fast, they have a great UI, and their customer support is great. I'm sure their tor site is much much better functionality-wise, too.
#TotallyNotBiased
This is my choice too bitmixer even though I don't use them daily but I love their design.
Cryptomixer.io in my experience because only for 0.001
BTC i can mixed coins and it went fine, i don't know about other services never try them before, i can recomended it for 0.001
BTC more than it, take the risk by your self.

There are a lot of mixers all over the net, there is bitmixer, coinmixer and also include cryptomixer. But I guess bitmixer is the most well known.