I am indecisive about choice due to room size

You can toss all the above bad advice. Some of it is outright plain wrong. Adding bass for example is exactly what you need. Your biggest problem is not size but being square, 12x12. But 16x16x8 would be bigger but at least as bad. Simplistic thinking combines with poor understanding. People hear the obvious boomy bass in a room like yours and assume too much bass so solve it with small speakers. Wrong.

I wouldn't go with any of the stuff you like but I wouldn't hesitate a moment to get better speakers simply because they're "too big for the room".  

Regardless of speaker you're going to want to control the lumpy bass identical dimensions causes, and early reflections. In that order.  

Lumpy bass is best solved with more bass, not less. Using multiple subs will allow you to put them in different locations to excite different room modes and ultimately achieve much smoother bass. Duke himself, owner and speaker designer at Audiokinesis, says the benefits of multiple subs are even greater in small rooms than large.

Just one of the ways people misunderstand the realities of the situation you're asking about.

Will the speakers fit in the room? Will you be able to place them with drivers at least 3 feet from walls and ceiling? Then they are not too big. 

It may work, but you may need to work on the room, too.

Smaller speakers have their own advantages, but bigger is not necessarily worse. Good luck and have patience.

Easiest way to get good sound in a square room. Use active speakers with digital control like Genelec, Dutch and Dutch,  Kii, new company GGNTKT might be another. There are others you can research. I've used passive speakers with outboard control it helps but isn't as good. You'll need less room treatments and get better results. One thing you don't need is a passel of subwoofers in that small room you can get all the bass you need for music with a  couple of Genelec 8361A. 

I am in a 12x12 with focal 1028be and Hegel h360 and still sometimes wish for more speaker. I think it depends on your listening style as much as anything else.

Many Japanese audiophiles do something highly counter-intuitive: They use large horn loudspeakers in small rooms. Speakers conceptually similar to the Altec Model 19.

But maybe they are onto something: These large-format horn loudspeakers have fairly narrow and unusually uniform radiation patterns. So they put less energy into the early reflections, and in general the narrow radiation pattern results in the direct sound dominating over the reflections. And the uniform radiation pattern means that reflections will be spectrally correct, such that they support (rather than degrade) the timbre.

I’m not necessarily suggesting a pair of Altec Model 19’s, but rather advocating the general concept of starting out with controlled-pattern loudspeakers when the room is challenging.

Also, if this is a dedicated audio room, given its square footprint, I suggest setting up your system on a diagonal. This geometrically precludes early sidewall reflections. It is the earliest reflections which most strongly convey a "small room signature". If we’d rather hear the acoustic signature of the recording venue, then in a small room the earliest reflections are the ones we most want to minimize. In my opinion.

And maybe even try your system ALMOST on a diagonal... like perhaps off by ten degrees.  This puts your woofers each at a different distance from all of the walls, which may make a worthwhile improvement in the bass region. 

Duke