I flush with AN and find the final result taste more true and less chemicals. I have tried not flushing and found the taste not too appealing. I did this on Black Jack and Grand Master.
I personally only use Advanced Nutrients. I like Iguana Juice, Micro-Grow-Bloom, Bud Factor X and Final Phase on a regular basis. I have compared them to several other brands and nothing comes close. I have been growing for about two years now.