To go from page to page you just swipe from right to left (next page) or left to right (previous page). Zinio is only about Magazines. If you are using it, how can you not notice it uses the retina display? Frankly, it is a very nice app for view magazine because it is so silky smooth. I use the Kindle app, too, but so far only for books, so I don't really know how well it works for magazines. I say go with what gives you the best price on the mag you want. Best to check them all, use them all, and view where you got the best deal.
One more thing also that I noticed is when you download a Magazine in ZINIO it dos not have a like the wat you Flip your finger from right to left to turn the page to the next page which is possible in Kndle is it possible in Zinio ?