Which one's prince Charming?

Just like Phillip when he first saw & fell for Aurora believing she was a commoner, Charming intended to marry Cinderella even if she wasn't from his legue because her background didn't matter to him. They have similar attitudes.

The one in Cinderella.

Assuming that Cinderella is the third princess and Snow White 1st,they'd probably get along well. Aurora in my opinion, seems to only think about Phillip so I doubt P.C and Phillip would get along.

I don't think Charming would be besties with the other classic princesses.
Prince and Phillip are very alike. They're adventurous (Prince was in a completely different kingdom when he met Snow, and then he searched a whole year after that for her. Plus Phillip seems to spend a lot of his time apart from other people, hanging out in the woods, presumably exploring), they're both extremely forward with their princess (Prince jumped over a wall and startled Snow, then began to serenade her. Phillip joined Aurora in song without warning, then grabbed at her a lot to prevent her from leaving. They have similar techniques. This I might let up though since Charming met his princess at a ball, when he's able to approach young women. So maybe he's just as forward as Prince and Phillip, who knows), they have different ways of showing their love and devotion to their princess(Prince searched for a year, a YEAR, then got his knees to cry at Snow's death. Phillip fought the mistress of Evil for her, and before knowing she was a princess was willing to start a war between two kingdoms to be with her. Charming had no clue Cinderella was a commoner, and I actually think she was a lady of some sort considering the house she lived in and her families wealth. Charming didn't go looking for his princess, and he had a much easier task than his other two classic princes. Charming showed his love and devotion by marrying her, which the other two princes probably got around too eventually. So his act of love pales a bit in comparison). I think he might be on good terms with them, he wouldn't be close though.
I don't think Charming would be close to ANY of them. He might be a bit closer with Eric though because they seem to have similar temperaments. Although Eric is more like the other classic princes than Charming too. But Eric seems a bit shy and soft spoken to me, Charming did nothing to prove to me he was outspoken or bold (besides approaching Cinderella, and again, it was a ball, he was a prince. It was acceptable). And they both also seem to spurn everyone's attempts to match them up with someone. Charming's father seemed like he'd been trying to match Charming up for a while before the ball. Grimsby had been trying to set Eric up I think (You're not still upset I didn't fall for the princess of blahblahblah, are you?) plus his pushing for Eric to consider Ariel. So, yeah.

I think Prince Charming and Prince Phillip would hit it off because they'd both dismissively complain about their fathers trying to marry them off. They both seem to spend most of their time far away from their palaces for long periods of time.

Prince Eric was in a different situation. He was in charge, so he didn't go far away, and not for extended periods of time. His mood is also a bit of a contradiction. On the one hand, he clearly enjoys himself during the opening scene. On the other hand, Carlotta says that she hasn't seen him smile in months.

@Jessikaroo - I don't recall anything about the two kingdoms going to war or anything like that. That sounds like Brave. Phillip simply didn't care about his royal responsibilities...or not as much as his peasant girl, at least. He gives up his crown and family and says goodbye (forever) to his father to go elope with the peasant girl. But there was never any threat of war, as I recall. The kings were friends.

Sorry, I didn't mean to make it seem like they were one hundred percent going to war over it. But there was always the slightest, possibility that Stefan would get angry about it. Even if it was the most minuscule chance because even the best of friendships can be crumbled by anger and hurt pride after all.

But beyond that, I just don't think Charming would be close to any of them personally, I just thought he might possibly be on better terms with Eric because of slightly similar temperaments and people pushing them to get married.

Also, I thought Phillip was perfectly fine with his marriage before meeting the peasant girl?

^ Phillip really didn't seem to mind marriage before meeting "Briar Rose", yes, which is a contrast to Charming who seemed to be annoyed with his father's tendency to want to marry him off, but still their morals are similar, they wouldn't marry without love and they didn't care if their girl was from a different legue. I can see Charming and Eric being friends too though, but not really close friends because Eric seems more adventurous and dashing than Charming.

@hajirah4: Cinderella is actually the second princess not the third.
Snow White (1937), Cinderella (1950) & Sleeping Beauty (1959).

The only time we see Phillip's attitude toward Princess Aurora before he falls in love with Briar Rose is when he's a boy and he sneers at her.

At the start of the movie, Phillip has been away for some time, and his father has secretly built a new home for Phillip and Aurora. He has arranged this and the wedding as a surprise for everyone, apparently, including King Stefan. Since this was a secret from Phillip also, there's really no way to know what Phillip would have thought of it. In fact, King Hubert doesn't even have a chance to tell Phillip about it during Phillip's brief hello-and-farewell conversation.