I've watched OITNB since season 1, finished watching seasons 1-3 of Wentworth before the current 4th season started, and only recently discovered and watched all of season 1 and episodes 1-10 of the currently airing season 2 of Vis a Vis. All three are women's prison dramas but besides that the only other trait they share is that they begin with a naive newby entering the prison. OITNB is an American production while Wentworth is an Australian production, and Vis a Vis comes to us from Spain and has been picked up in the UK under the name Locked Up. OITNB is by far the most light-hearted of the bunch with more comedic moments than the other two, it also has more annoying characters than the other two, and has suffered one less than stellar season. Wentworth, by comparison, is very dark and has maintained a very consistent level of great drama throughout its four seasons. Vis a Vis is the newest and as of its 2nd season, it may be on par or darker than Wentworth, it definitely has the most badass characters both inside and outside the prison. Of course this is just my opinion but all three dramas are very good and completely different from each other, so if you like one I suggest you try the other two.