Wow, tons of options. Total water volume? Is there a sump? How much room do you have in sump, if so?
Reef Octopus makes some great, easy to use skimmers. RLSS and Aquamaxx are also very nice and efficient.
Tunze is a great company but, I haven't used any of DOC skimmers. Their pumps are solid, so that's a big plus. They look kind of undersized. I would want a bigger collect cup on that size tank.
The Red Sea skimmer isn't highly rated. That looks like a nightmare to clean, and again, that cup looks tiny. I have yet to hear anyone say they love this skimmer. It also looks like it need a feed pump, which is a negative in my book.
Just my .02