My favourite thing about Vala is probably Genie¹. Having an alternate syntax is a great idea, and I often wonder why we don't see it more often.

I was always a little sad that Vala didn't really catch on inside Gnome(or at large), as it is a really nice language to code in and working with GObject feels very natural within it.

¹ https://wiki.gnome.org/Projects/Genie