I've used both xournal and liqbase for note-taking (graduate-level engineering course), but at present I almost exclusively use xournal.

Why? Mainly, portrait mode. As one or two other posters noted, scrawling text tidily onto the screen is much easier in portrait mode, and liqbase doesn't support that at present. I'm not sure of the technical details, but I had thought that XV breaks in portrait mode; I recently discovered that the internet call app handles it just fine, though, so it may be possible...

That's perhaps the biggest improvement I could see for the way I use it; I'm considering writing a liqbase-xournal file converter, but I don't think that's a big deal either way. A practical lock-in (no conversion tools) is no big deal, as long as I know I can overcome it if/when I need to.

And searching the graffiti wall is much easier than opening 5 different sets of notes when I need an equation; liqbase definitely wins there!