For a focused project, electronic is almost certainly better (and if you initially write on paper, it's worth transcribing). But for my purposes, I'm mostly journaling my day-to-day activities. I don't think I'll ever want to search for that time I needed to get caffeine free Diet Coke and had to push it forward for three straight days (that would be today...)
A really nice thing about bullet journaling, relative to other forms, is the index. I can keep my old journals (labeled by date range) and look up stuff that might actually be interesting in the future, like "Jim Campignolo workshop notes".