I recently was making this decision to put some QUALITY flow into my tank (i.e. ditch the "I'm a cheapskate" SEIO pumps).
I liked the ability to control via the tunze (the wireless controller device was still in testing phases), but people kept warning me about huge honking pumps inside the tank. As mentioned the cost of a 6100 (equivalent of the Vortech in terms of flow) is very similar to a Vortech. But the controller cost a bunch as it stands. Ultimately I decided on the Vortech because locally their more available that tunze pumps, and I got a kick-arse price on it.
Now all this being said, I really like the low profile of the Vortech, it's still a large system, but compared to Tunze (which I've seen in person) this is nothing. The lack of aiming really becomes a non factor at this level as well, the flow of both is really dispersed and you don't want to lose that energy by aiming it towards a piece of glass anyways. Having everything electrical outside of the tank is a wonder too, not so much for the scare of electricity in the tank but more for the asthetics of not having wires going into the tank.
Now does that mean a vortech is for anyone? Nah, if you had some situation where you'd want to hide the pumps from normal view, and as a result needed to aim them at an angle, then maybe a tunze would be better suited, or if you have rather thick glass/acrylic, then a Vortech (at present) would not work. Either way you go they're both great products. However for my applications I'm happy I went with the Vortech, not to mention the controller comes with the drivers (now), so if I want to upgrade in the future with another vortech I can do so easily, with the Tunze setup you have to plan ahead if you're thinking of more than one pump on a controller.