RTW patched up to 1.5 was quite playable. The versions before that were fine in the early days but once we figured out all the flaws of the game, quickly became completely unplayable. I mean honestly, an AI who forgets its orders after loading a save and marches away from easy pickings? Come on.

BI wasn't bad but required the player to do some pretty gamey stuff to survive. The Western Empire starts the game like -20,000 in the red in income per turn. Yeah the West should be hard, i get it, but impossible isn't fun.

Lots of people swear up and down when it comes to Europa Barbarorum as well, but it's not for everyone. The mod has a very specific way of doing things and if that's not you for, you won't like it. But hey it's a free mod for a game you own and has significantly improved the game for a lot of people. Worth a look imo.

As for which is the better game: BI is probably the most polished experience by far. Vanilla RTW is unplayable unless you get it patched, and even then, it's got some dumb stuff. Egypt. Enough said.