Do you know what is the best gtx 1080 at this time? Or does all brand the same?
All GTX 1080's are similar and have the same architecture, but no two models/brands are the same.
yes I mean is their performance the same? or is there a brand that offers some extra boost or like that
There is not necessarily one specific brand that is better than everything else. It is all about balances and compromises. There are some GTX 1080's that are better than others (e.g. better cooling, higher clock speed, more memory, etc.).
Generally they're not exactly the same but performance is very close in any given price bracket, I don't think it's worth spending any time over tbh & I'd just go for whatever brand is cheapest.
Is it worth to get 1080 at this time? or do u think 1080 ti will be released at this year as well?
I think a 1080ti would maybe out very late this year or early next year, once the pascal titan is released that should give us a better indication as recently the x80ti follows that by around 3-6 months.
I have heard the founders edition cards are clocking very well and nvidia might have sorted through the cards and hand picked the FE cards. Can't go wrong with an EVGA FTW either.