Do not know if many know about this, but it sounds very interesting to me

btw: what is the better library's for kontakt, when it comes to strings, vocals, piano, flutes
and all that stuff..

8dio is top-tier stuff. The brand is fairly new, but the developer has been around for a long time (originally as Tonehammer, which spawned both 8dio and SoundIron). Its founder is an accomplished composer of big, epic pieces for video games and movie trailers, so a lot of 8dio's products lend themselves to that genre.
 
The better string and orchestral libraries tend to be pricey. Top of that food chain is probably Vienna Symphonic Libraries (VSL). Their everything-bundle will set you back about 6 grand (!). But there are plenty of other orchestral libraries that'll do a fine job for much less, including 8dio.

You're asking the unanswerable question.... spend some time over at VI Control's forums... So many choices/options/considerations... There's no one shop answer. They are a great community sharing thoughts on these very questions... top notch cinematic/game/film/music folk.... here  Spend a night, join...search....
 
I own many 8dio libraries.  I'd wait for their periodic sales... very innovative company and their more recent stuff has nice GUI improvements but I have gravitated to Spitfire Audio's Albion range (here) as it's so exquisite and best bang for the buck for orchestral stuff. Albion 1 gives you a HUGE arsenal of power... Kirk Hunter also has bang up deals for quality stuff.  
 
See related thread below from East West Lurker introducing himself...
 
 
 
Best of luck.  
 
By vocals, you mean choral?  sooooo many choices here too... Several years ago I ended up getting the CompleteComposerCollection from EWQL  which fills a terabyte HD with Orchestrals, voices of passion, choirs, beautiful pianos, and much much more... price was irresistible and you pick your bits to complete your package.  They just had huge sales and  Not Kontakt... Play engine, which is fine these days... might be the way to go to cover lots of bases...
 
One last final suggestion.... Symphobia 2014 edition!  Guy Rowland, from VI Control just did a bang up 3 part review of it and I am hugely frustrated he didn't do it before I bought OE 1&2... It is amazing.... And his videos are both thorough and hugely fun to watch...on a good system with studio sound.... you'll really learn all you need to know....
 
See them here:
part 1
part2
part3 multies 
 
enjoy!
 

Love Symphobia. I could lose myself for months if that was the only instrument I had. 800 bucks, though, so it won't be living on my drive anytime soon. But check out this improvisation video to get your GAS going.
 
BTW, if you want to have that kind of improvisational fun on the cheap, check out Indiginus' Solid State Symphony ($40).
 
Here's a brand-new review of 8dio's Grandiose Legato Strings from SoundBytes, just out today.

bitflipper
BTW, if you want to have that kind of improvisational fun on the cheap, check out Indiginus' Solid State Symphony ($40).

+100 for that one. Its sampled synths, not sampled real strings but it sounds amazing and has some great features.

I have 8dio "Adagietto" which is like a collection from their various string libraries. It's awesome. They have a very expressive bowing patch that I don't think others can emulate. And I think Adagietto was $150 or so?
 
 
 
 

Soundblend
Do not know if many know about this, but it sounds very interesting to me

btw: what is the better library's for kontakt, when it comes to strings, vocals, piano, flutes
and all that stuff..

8Dio is one of my favorite sample library companies. I own a ton of their libraries and a number of them get used, almost without exception, in every piece of music I write (I write mainly video game soundtracks). I definitely recommend waiting for one of their big sales and pick up a bunch of the ones you're eyeing all at once since you'll get a big discount. 

8Dio Libraries I have that I can attest to their quality:
Adagio Violins, Violas, Cellos, Basses
Adagietto
Claire Flute, Piccolo, Clarinet, Oboe, Bassoon
Steel String Soloist (Acoustic Guitar)
Post Apocalyptic Guitar
Hybrid Tools Vol. 3
Music Box
New Angels
New Alien Drum

8Dio is a good manufacturer, but I'd take some of their stuff with a pinch of salt. They do deep sample stuff, but alot of their "niche" libraries are the sort that you can find equal and cheaper alternatives. Personally I love Adagietto and the Agitato strings, but other than those a lot of their stuff seems go to unused since I have "better" stuff from other manufacturers as well. 
 
Their pricier stuff though is pretty much the top of the line.