people will just netdeck what is considered the best for each week challenge, people who wanna have super fun decks will just shoot themselves in the foot like in ranked playing fun deck, thoughts?
The meta decks are often established on sites like Hearthpwn after weeks and months of testing from lots of sources. If it changes up every week it's going to be tough to get enough data to be like, "This is the best deck for this brawl." There will be a section, it will be theory-craft, and then before anyone has solid data it's a new brawl.
I think the OP's gripe is that even if people can't come up with the absolute best and most refined deck each week, there will be decklists floating around on how to best tackle the brawl each week. Most likely, the top voted one will be netdecked a lot and instead of everyone making their own decks and having their own ideas, a lot of the time you will be facing the same netdeck. That much is pretty inevitable.
It's pretty obvious the main purpose of tavern brawl is to make it slightly easier for new players to get into the game and complete dailies. Between ranked, casual and tavern brawl, you would definitely have a better chance of winning in tavern brawl because you're not going to be up against decks that have been refined over months.