I watched Lain with the subtitles on and I still won't claim I understood all the lines.

I'm pretty sure many of the lines are _not understandable by intent_, even.

"Present day... present time... ahahaha!"

"And you don't seem to understand..."

Ironic that it holds the first place by understandable lines. The vocabulary isn't the complex thing - it's the content itself that eludes understanding.

Surreal and dreamlike - almost as if inviting you to connect the dots, but not giving you the labels, not giving you enough dots or an obvious enough outline to connect them confidently.

It's funny that I remember basically nothing of the series anymore... except that it still didn't quite make sense to me at the time.

The latter Evangelion episodes seemed similar (but not quite as crazy as Lain). Apparently they're making a follow-up series too!

Serial Expirementd Lain is basically the Ulysses of anime. Super dense and cryptic by design.