I'm not very familiar with the strengths of the different tunzes. But if it were me I'd get two of them no matter which version you decide on. I'd put them in the back corners pointing to the front/center. From the research I've done I can give you the pros and cons I've come up with. Anyone else, please feel free to correct me if I'm wrong..
Tunze pros:
very minimal energy usage
Optimal flow pattern
high quality product
can be hooked up to a controller to simulate waves and such
Tunze cons:
large footprint (takes up the most space of the three types mentioned)
wires in the tank
heat transfer
Vortech pros:
almost no heat transfer
very wide optimal flow pattern
undertow effect
doesn't take up a lot of room in the tank
no wires in tank
controllabe, can create wave effect
battery backup in case of power outtages
minimal energy usage
Vortech cons:
can't aim it (but this doesn't reallly matter because the flow pattern is so wide).
some people say its loud but I don't think so, you can only hear it when its cranked IMO
the first version had a couple bugs. But as far as I know they're all fixed now.
Closed loop pros:
no heat transfer
practically invisible in the tank
can be done cheaply
Closed loop cons:
cannot be changed easily once installed
Not as energy efficient as the other two options
you may need to buy expensive wave devices like sea swirls and wavy seas to break up the flow
takes a bit of plumbing know how and planning
Potentially need to put holes in your tank
can end up being very expensive depending on how far you want to take it
can also be very ugly and bulky under the tank if you don't plan it out right
For me the most important things were heat transfer and real estate in the tank. I also HATE seeing wires in the display tank. I bought everything for my closed loop before the vortechs came out. So I've decided to use both a closed loop and a vortech. There's my 2 cents!