Left Behind and Battlegrounds are outstanding maps. You'll want to keep both if you like Quake 3.
It's safe to skip the 2 remakes and the same goes for Panda's map unless you play E+. I didn't try the castle map yet, I hate castles.
You Hate Castles???
Man, 'castle' from Tiddles is one of my fav ffa maps :)
If you got a link to that one I'll try it.
(When I type 'map castle' in my Quake installation an FFA map loads that both looks and plays ass. I've seen some screenies of maps by Tiddles and I'm quite sure that he didn't make this one though, hehe.)