All 3 brands are equally good in my opinion, its more of your personal choice. Read on reviews for all 3 products, and pick the one u like best.
If you wan good support, try skimz or deltec. Reef depot does great customer service for deltec, drop them a mail, and they got back to me immediately, only downside is that the product must bear the reef depot sticker. Skimz, well...its under AM, so u probably wont have trouble getting warranty claims or supports. As for Vertex, i don't have much experience, but you can always check with iwarna before purchasing.
Both needlewheel and venturi has its benefits and downsides.
Needlewheel: Creates more finer bubbles, hecks bubbles apart, resulting in better foam head with dense froth. Requires a smaller pump and footprint in comparison, lower wattage. Downside : Lesser waterflow through the skimmer, chance of damaging living critters, needlewheel impellers may cost more for replacement.
Venturi: Moves a large amount of water, increased contact time due to whirlpool effect within chamber. Besides cleaning the venturi valve, its pretty much maintenance free. Downside is that it requires high pressure, dedicated pumps which can deal with back pressure in order to function well, properly rated pump size to maximise efficiency of skimmer, heat from the pump, higher wattage of running.
Personally, anything more than 300 gallons, its worth going venturi. For smaller volume, needlewheel would be good. Thats probably the big factor why the marine industry made the switch to needlewheel.