NL has no queues, chat works more often, fewer players, cheaper items, and better giveaways. You can probably get tons of free high tier gear when L converts to NL.
L has exclusive unique and runewords and more opportunity to make fg. Ladder enemies have slightly more hp, but it’s not noticeable.
Once you get geared and running with a small pool of fg beyond what you need, I’d say NL is better for general QoL until they fix the servers. There is no actual PvM content (other than items) that are unique to Ladder nor are those items necessary to clear all content. So, if all you want is to “beat hell” or do ubers, NL is quite fine.
Lemme know if you need some starting gear on either.