which better...

There are many great speaker brands out there.
My choice would be Paradigm, excellent products and reviews.
If you are more into music and listening to your music in Stereo I would recommend Paradigm Studio 100's. If you are more into home theatre then I would recommend Paradigm Monitor 11's. The reason being you will just save yourself some money if you really only need them for home theatre.
I have both these products and I listen to music in Stereo. I recently purchased the Studio 100's and have moved my Monitor 11's to the rears.
In the professional reviews it is hard to find a bad review about either product, I don't believe you can go wrong with either choice.

The Studio 100 is by far the best speaker you have on your list, of course this is just my opinion.
If you can afford it grab them and the other 4 channels that match and never look back.

What about PSB T5 + sub or Paradigm's SE series? With either you should be able to afford a sub. Good 5.1 is better than lesser 7.1

There are other options too: what is your room size, how loud do you want to go, what is your amplification?

Ron

Most people want a sub to go with the surround sound regardless of which main speakers they choose.

Buy a sub online to get maximum performance and value. You don't need to match the speakers and the sub (i.e. there is no need to buy the same brand).

-Max

You can get the BIC America F12 for $200... it's a pretty decent sub, depending on the size of your room. I would go with the Paradigm if I were you. If I had the budget, that's what I would buy.

What is your budget?

From your list - my vote is for Kef IQ 90 or Paradigm Studio.
I would look at the Marantz 6005 receiver. Get a sub from
a company, who are real subwoofer people.

The KEF IQ90

I like the Definitive - however, I have not heard the STS.
My favorites are the Boston VS series speakers, NHT or
Focal speakers. However, you will do fine with the KEF,
Paradigm Studio or Definitive.
With a 16 x 13 room - good bookshelf speakers will work.

I prefer PSB at equivalent pricepoints to Paradigm and am not alone - it's a preference thing though, they are both excellent.

Amplification would include AVR, but you seem to prefer quality over volume, as do I.

Paradigm, KEF, PSB, Revel, B&W, Dali, Monitor Audio (missing some I'm sure) these are all really good speakers that come down to (again) individual preference.

Go listen!

Ron

KEF iq90 out of these choices.

Don't wait for every body to agree on the same speaker. Go out
and audition some. Check with HSU, SVS or EPIK for a subwoofer.

Since your budget is $5200 - it is better to audition. Yes, it can
be tough - however, you don't want buyers remorse with that
kind of money.

I completely understand your position Saher. But Ziegl is right in that it is difficult for everyone to agree on a choice of speakers. If your AVR choice is Marantz 7005 - you are looking in the $1000 - $1200 range. That leaves about $4000 for speakers and sub. The other choice is to ask if any of the members here stay close to you or in your town and request if you could listen to their set up. It will be a better demo than any store can do.

I am in the same boat as you and considered 2 of the same choices you did - Def tech STS fronts or Paradigm Monitor 11s. I demoed the Monitor 11s and also heard the Def Tech 8080s. They were good speakers. Currently I am looking at the Pro-10s for the front stage. Would love to listen to them if I could.

It is not easy but do your homework. Good luck!

Now you know that you do not like the Kef iq90.
That should prove how valuable listening is.
Take your own CD with you when you go to listen.
With $5200 budget you have a lot of choices.
Where are you located ?

Its hard to make a recommendation.
Out of all the speakers you have listed I like the Studio 100 best and iq90 second.
Take your own CD with you and listen to the speakers available and then tell us what you liked the best and why you liked it.
Also what you didn't like and why.