With the Fast option
What tool/website you used to check this score?
Chipmixer had higher score because they existed much longer, so everyone had time to add their address into their tracking systems.
New mixers will naturally have lower score at beginning, but I expect it to grow in future with both fast and note option.
As of now "no fee" is correct. You are free to choose 0% and it's defaulted to that on the website, anything over it is treated as a donation. Some users may choose a number over 0% not because they want to donate to us, but for extra privacy, so the option is there regardless.
How exactly higher fee means extra privacy?
Is it similar like chipmixer had with their service or you are using some additional mixing for higher fees?
Anyway, it was good decision to make, it should attract more users for sure.
PS
I think you should add more information and links about your service on your bitcointalk profile, it looks more official that way.