I have a Yamaha as-2100 integrated amplifier, can any one advice for a speakers for this.
Dude!  You need to give us more info such as price? size of room? what do you listen to?
Com'on spill the beans!

Vandersteen 2Ce Sig II, biwired with solid-core cable like Anti-cables. Set them up correctly, do some room treatment at first reflection points. Enjoy the sound.
+1 on the Vandersteen's. Also check your local "craigslist" to see whats available locally. Nothing better then to hear before buying.
You could probably drive a pair of Magnepan 1.7i the room has enough size. Best thing is to get out there and listen.
Not enough power for 1.7s.  The vandersteens are a good suggestion.  You should also look at Salk Song 3s, Revel F208s.  
Thank you very much for your opinions. How about used Aerial Acoustics 6T because  Sensitivity 90 dB for 2.83 volts at 1 meter on axis. 
I have the A-S2100 & have it paired with KEF R-900’s, I love the combo completely. I have the KEF R11’s in a different system & feel it is an overall improvement over the R-900’s...I think either the R-900 or R11 would work very well for you paired with the A-S2100.
Thank you very much for your opinions. How about used Aerial Acoustics 6T because Sensitivity 90 dB for 2.83 volts at 1 meter on axis.

C’mon dude.  Really?  You’re talking specs?  How about Aerials?  How about ANYTHING???  We have absolutely NO idea what you’re looking for here.  What do you have now and what are you looking to improve upon?  What aspects of speaker performance are most important to you?  Dynamics, tonality, detail, warmth, imaging, soundstaging, PRaT?  You’ve given us absolutely NOTHING to go on here to help make a meaningful recommendation here.  How the hell would we know if Aerials or anything else would be a good recommendation without knowing what sound reproduction and speaker characteristics are most important to you?  A little common sense and effort on your part here.  Jeez. 
For that size room you should get a nice pair of stand mounts with a subwoofer!
For $5K ballpark you can probably find a used pair of Vandersteen model 5s or 5As.  There were a few for sale asking in the $6K range.  Since they have a powered sub, you may get away with the power you have and they will only get better when you upgrade.
I don't know, maybe a pair of Legacy Focus? And I still think Vandersteen's are a good idea.
Thank you very much for your guides. Is there is any who has experience of using  Salk Song &  Vandersteen 2Ce Sig II. Because after going through all I have decided to by one out of above two. Please advice.