Hmm that's an intresting question, lets see.
***Warning may contain spoilers***
Malchior, well she had as much as a crush on him (when she thought he was Rorik (sp?)). I would say she would like a guy like him, some one smart that would listen to her and understand how things are for her. Also I asume maturity is a big part of it.
Robin, she may like him as he always showed her there is hope but he's with Starfire and I dought she's the type to get between them. Also at the end of the Trigon saga she only hugs Robin.
Beast Boy, sorry fan girls but I just don't see this happening as a relationship. I know that they are close and all, but he's just to immature for her in my opinion. In most episodes she is either making jokes about him, or he some how offends her. Also she might be the most emotional person but when it comes to remance she usually shows emotion, the white robe and cheery attitude around Malchior, and the hearts when around Aqua Lad for the first time. Then the time they actually had a chance for a romantic momment, episode The Beast with In, Beast Boy kind of breaks the momment. Finally there is Terra and he likes her, it's quite evidant even in the last episode of Teen Titans. I think that Raven and Beast Boy have a relationship but in terms of big sister and little brother.
Note: I'm basing my facts on the TV show and I heard they have some relationship in the comic book but I also heard Beast Boy is more mature in them.