Lightning is perhaps more private than on-chain transactions but lightning has many issues, even the most dedicated of Bitcoin lightning users have complained about it.
Whereas monero cuts that all out, and makes it easier for average users to transmit value.
I prefer Monero simply because I don't need major amounts of it to transact, it has an easier barrier of entry, and because I don't have the potential to lose funds like lightning does with improperly shut channels.
Now if I had a lot of sats, I would do so through something like Zeus maybe but I don't have that much BTC, so I'd rather use the more accessible tool to me.
(^ That's just my thoughts, and opinion, I haven't used Lightning enough to really say)
I think this article below is a fair summary.