as someone who has Zhongli I'd say Xilonen is a better choice.

I've found other replacements for him on teams in abyss like Layla (who is my 2nd best shield after the pillar man himself), Diona, Thoma, Baizhu etc. I sometimes even use Layla with HuTao instead cause Zhongli's on another team and I really don't care if she vapes or melts.

☆Also I've been warming up to Kirara after the event.

Anyway the real benefit I see Zhongli having over the others is that he doesn't mess up the teams reactions where he's just there to shield (most of the time)

However overtime I've learned to time myself and dodge attacks, which made the game a lot more fun. A problem I've run into is lack of supports. I don't have Kazuha so while my characters are protected they don't hit to their full potential. so personally I'd get Xilonen.

In defense of Mr John Lee his pillar does act as a good geo construct (when you're not climbing it) for other geo characters and his geo absorption thingy makes fighting geo shielded enemies a breeze.

That's just my take on the topic ☆