Two medium size woofers Vs One big size woofer

Great, if that's the case, I get good sound along with aesthetics.

There's no substitute for surface area and maximum linear displacement in absolute terms. The idea of small drivers being faster is rarely proven.  Two 8" drivers have about the surface area of a single 10" driver but often with lower impedance.  It's not like you get a 16" driver by buying 2x 8". Also, the 8" drivers tend to have shorter displacements and power handling, so assuming they had the equivalent surface area of a 16" (and they don't) they'd never have the same linear movement capability.

Having said this, I will say I'm a big fan of 2.5 way systems for their efficiency and foot print, but they do tend to have lower impedance with the parallel drivers which can make them underperform with less capable amps.

The big issue in terms of having "fast articular bass" tends to be that the lower you go, the more issues you run into in a room. A speaker that is anechoically flat to 16 Hz may sound really crappy vs. a smaller speaker which is flat to 40 Hz as the big speaker will aggravate the room modes more.  

There's a big difference between the anechoic bass response of a speaker, or the -3 dB point, and how it will sound in a room. Smaller is often better. 

two 5" woofers is equivalent one 7" woofer , not 10"
this is simple , check any speaker design book

approximately

I have two Vandersteen 2wq subwoofers. Each has three 8 inch drivers driven by a 300 watt internal amp. They have a "Q" control on the cabinet back to increase or decrease the tautness of the sub response. The three 8" drivers with the "Q" set low provide amazingly tight bass. If you want it to boom, for home theater movie reproduction you just turn that dial up.
I just bought a new disc player and power cord for my system amplifier. The disc player is rendering a tighter bass profile and the power cord (7 gauge) has really given heft and gestalt to the bass and system sound overall.
On the other hand, one large driver can do a nice job especially if it is used in a servo controlled system.