Null-Subject and Pro-Drop
Aesthetically, I really like languages which are null-subject or even better, pro-drop. There's a certain elegance to omitting pronouns whenever possible; a simultaneous compacting of information and elimination of redundancy. Some languages like Persian compensate for this with markers on other words. For example, consider the following exchange rendered in Romanized Persian, low register:
"Amir ba mashinesh chikaar kard?" ("What did Amir do with his car?")
"Furukhtesh." ("He sold it")
Here the second sentence is just one word: the verb for "sell" put into past tense and declined for third person singular subject and third person singular object. No pronouns. Short and fully intelligible. Really pretty.
Other languages don't even bother marking for the missing pronouns, they just say "screw it, you know what I'm talking about." Look at Japanese (pardon any minor grammatical errors):
"Yuuta wa jibun no ringo ni nani o shimashita ka?" ("What did Yuuta do with his apple?")
"Tabemashita." ("He ate it.")
The second sentence is just the verb for "eat" conjugated to past tense. No markers at all. But the meaning is, so to speak, pragmatically inferable and that makes Japanese really nice.
Plain null-subject is cool but not as pleasant. Apparently all the Romance languages save French are null-subject - of course it has to be the only one I intend to learn which isn't null-subject. Aesthetically it's a nice feature but somehow feels incomplete compared to totally pro-drop languages.