I honestly don't mind. There's advantages and disadvantages to all three of them. There's also advantages and disadvantages of Cyborg as an opponent.
Holly Holm is the interesting stylistic matchup because she'd theoretically be the best at employing a distance striking gameplan against Ronda. She's marketable as a boxing champion who's undefeated in MMA, in a time where the media is always asking "would Rousey beat Mayweather?". The problem is that she hasn't looked great in MMA or the UFC, lacks power, and possibly even has chin issues and is nearing the end of her career. I think the UFC wants to use Holm as a contender before it no longer becomes an option. They want to do the Rousey vs boxer fight while they have the opportunity. Holm is nearly 34 and could lose to someone else in the division, derailing the fight and hurting its potential marketability.
Miesha Tate set the record for longest time in there with Rousey both times she fought her and was more competitive than everyone except Liz Carmouche. Miesha having a rivalry with Ronda and also being attractive helps the marketability of the fight. She also maybe deserves it on merit, being on a 4-fight streak against good fighters in the division. The problem is obviously that they already fought twice, and even though she lasted longer than other opponents, she was still pretty much dominated. I think Rousey/Tate 3 could still be an option a year or two from now, and that's why they're willing to take Miesha's title shot away in favor of giving it to Holm.
Amanda Nunes destroys people in the first round, and she looked particularly good against Sara McMann. On a different day, she would have finished Cat Zingano in the first round too. The advantage of giving her the shot would that it'd be a fresh matchup and maybe the most competitive of the three. The disadvantage is marketability-wise she's similar to Bethe Correia, whom Ronda just fought. They're both angry Brazilian fighters, and have aggressive styles. She's lost before and come back from them, and is the youngest of the three contenders, so you can see why they aren't rushing to give her the title shot.
Julianna Pena could be a contender soon too. She has to beat Jessica Eye at UFC 192. She's Miesha Tate's friend and training partner from TUF 18, which could add something to the selling of the fight. She's also a finisher, on a 5-fight streak with 5 finishes, the last 3 being by TKO in the first round.
The Cyborg is the best fight becuase she'd be the most competitive, and it'd probably be the biggest fight business-wise too. The disadvantage is the same it always was; that she hasn't made the 135 lb limit. She's bigger than Ronda and has been caught for steroids before, which is maybe why the UFC is so adamant that she must make the weight. I still think it's possible they could do the fight at a higher weight, but right now they don't seem interested in that.