I thought this was interesting to look up: I wanted to see how much I've played the Fighters Pass characters, so I combined the offline/arena and quickplay data, and voila:
Joker: 1:51 (35 battles)
Hero: 0:05 (2 battles)
Banjo & Kazooie: 2:39 (53 battles)
Pretty telling that Banjo already has a lead over Joker despite being out for what, three days?
I also ran through all their Classic Modes and used Joker and Banjo for their Spirit Boards. (RIP Hero)
Now that I've settled into B&K being my co-main, I assume I will log in several dozen hours into them by the end of Ultimate's life cycle. A shame about Hero, I suppose, his stage isn't even that great (while Mementos and Spiral Mountain are god tier), but 2/3 ain't bad. Doubt I'll play Terry much, but his stage could have great music to make it worth it.
For spending $18 after gold coins, it's not a bad value. The Spirit Boards alone probably make it worth it. I'm anal about having all Smash characters/stages even if I don't use them much, so I wonder how much I'll be playing the post-FP DLC characters when I'm basically settled into K. Rool and Banjo.
Speaking of... for comparison, the King's stats:
King K. Rool: 85:45 (1971 battles)
It's kinda hard to appreciate all of the characters when there's 80 of them. Like, I was really excited for Snake to come back, but between all of the shiny newcomers and my old main Cloud, I've barely touched him. I didn't even think I would end up co-maining Banjo until he came out.