I think that you need to be a little clearer with what information you want Nibras. Are you asking for the best DNA stains for either  agarose or PAG gels?

Thanks for your replay. Actually for agarose. 

Some useful information as I think 

https://www.thermofisher.com/iq/en/home/brands/invitrogen/molecular-biology-technologies/agarose-content-with-tips-and-tricks.html

http://bitesizebio.com/13520/how-do-you-stain-your-dna/

Thanks for your answer. I'm appreciated.

I think before staining would be more easy and more valuable

Thanks for your answer.

Regards

It's very important question