I've read all the articles and studies which just debate back and forth. But, l would like some honest, personal opinions whether or not running with nasal strips really helped your performance.
and what brand do you use?

Yes it does, you are supposed to breathe in your nose and out through your mouth (more to relax during a race then anything) and l have found it much easier to breathe---especially when you have a clogged nose or something else like that.

It has helped me especially during cross when l ran a sophomore race. l improved my time that l raced on the same course two weeks earlier by 17 seconds from 17:44-17:27 for a 5k ! Same conditions too!