Is Naked Liz worth leveling if...

From my experience I say - yes, she's worth leveling
But why?
Because in my opinion it's best to have at least 2 max-leveled servants from each class (regardless of rarity). And you've got Rama. He's good but I think he needs a partner to fight vs. all those lancers :) For f2p/beginners leveling up a free 4* servants is always a good choice: you get them for free, there's always one ascension material (so you don't need to bother where and what should you farm) and the most important: it's always possible to have it NP5.
Furthermore, Liz seiba has damage buff on this event so she can wipe out lancers/berserkers and help you aganist all other classes
Just go for it :D

I hope I helped :3
And sorry for bad London, it isn't my native language

Bear in mind that due to the 100% extra damage, she deals regular damage to Archers.

Yes only because you dont have many sabers ,you always want to be able to create anti-lancer team and she have bonus for event and so why not.Also i really liked her animations ^_^

Only good thing about her is defence ignoring NP 5 imo. you not gonna use her when you get better alternatives.Shes not like saint martha(aoe debuff removal) or Nito(insta np death chance) she doesnt have anything usefull to make you pick her instead of better alternatives so shes just mediocre.

İf only she had good 3rd skill then she could have been good servant.

So many people asking Liz vs Rama...
Welfare servants are generally great. Liz's shinning point is her amazing NP strength.
However, Rama's superiority is his 1st skill is amazing. When lv 10, both star abortion + 100% critical-up is no joking. Also CD is only 4 turn make his performance can be compared with Altera and Okita, typically if you have 4060 Merlin/Hans/Nightingale/Waver and Blonde Anniversary MC.

Overall, Rama is more worth in long-term investment typically for his lv10 1st skill. Liz is okay for max level, but maxed skills? Depends. She need so many medals.

Rama can be used to OHKO or defeating neutral servant easily with his kit, he also can survive in a longer fight.
He truly shine with Crit Supp like Hans, Caesar and Waver. For 2030 substitutes, you can use any available Crit star gen CE's on your Arsenal.
For me, i field him with Hans, Leonidas/Helena and Caesar because i don't have Waver. He deal massive Burst damage.
For his Ce, you can use Victor of the moon, Joint Recital, and Knights Dignity to further increase his damage.
He's has similiar playstyle to Scat, Brynhildr and Li Shuwen.
The only drawback is he's more expensive to raise.

Liz has pretty solid build with her non reliable 3rd skill, can still hit hard because she is also a Buster servant with powerful Buster buff and come as NP 5 welfare unit.
Think for a little, maybe she doesn't have any Crit up skill so you can use Crit Ce's on her.
For more consistent gameplay while using her, i would prefer a Buster CE's with NP up option or NP damage up CE's like Kaleid Ruby, LZO, Heavens Feel and Halloween Liz.
It's up to our conditions and the enemy type of course.
The team comps while i using her is pretty much the same as above.
She's cheaper to raise and like mentioned above, her drawback is her 3rd skill.

Both is a durable Buster servant with a pretty solid gameplay also pretty strong boss killer.
You can raise them slowly, no need to rush.
Choose who's really compatible to your playstyle or is one of them is your favorite ?
There's tons of team comps and CE's combination for them, my explanation is just an example.
The choice is yours, i only help add up a bit.