I have heard the Triton Ones and thought they were very good. You will want a center speaker that matches your left and right, so if you go with Golden Ear, you will want a corresponding Golden Ear center speaker. The front stage should be timbre matched! You can also use a bookshelf speaker as a center with no problem, in fact, a bookshelf speaker might perform better because lining up drivers on a horizontal plane can like what the Golden Ear center speakers do can create lobing problems.
Read this if you want to get in depth here, but if you want the short version, here is a statement from the article's summary, "Look for designs that have a vertical arrangement of their tweeters and midrange drivers. Look for planar, coaxial, lower tweeter crossover points, higher order crossovers, or other designs that avoid or minimize the “double slit” effect and incoherency that can result." What that is really saying is try to avoid speakers where the drivers are horizontally arranged.
Another thing is, the major advantage tower speakers have over bookshelf speakers is bass extension. However, when running a sub like the Hsu, that extension will not be used, because you will likely be crossing over at 80 Hz or higher, which is a point of extension most decent sized bookshelf speakers can dog down to, so the chief reason for getting tower speakers is negated. You might consider getting the Golden Ear bookshelf speakers for fronts instead of the towers. With your intended arrangement, you can even use the subs as bookshelf speaker stands to save floor space as well as money. The
ideal is to use identical speakers for all channels anyway, so if you can accommodate a bookshelf speaker as a center speaker, you will not only have saved money and floor space, but you may end up with a better sounding system overall as well- from the above linked article, "To get the most cohesive performance out of perhaps the most important channel in your home theater, strive for getting a center channel that is identical to your mains." If you want to stick with Golden Ears, I would be looking at Aon 3 bookshelf speakers for front left, right, and center.