I'm still learning so please bear with me. I'd like to buy a coating this weekend during the Labor day sale but, which should I consider? Which one would give me the most hydrophobic, impervious surface, that is microscopically smooth? These are the two most important features to me. Thank you very much for your time and consideration! 
P.S. It would be nice to be able to top it if I chose to but it's not necessary.

P.S. It would be nice to be able to top it if I chose to but it's not necessary.