Realistically... 2k

Well the only servant I have at np 5 is melusine at a cost of about 300 quartz + gssr

It is insane luck since it is not reasonable to even get np1 with 300

4500 Quartz and don't roll until NA gets the refreshing pity like JP has is the only correct answer. As for who to get, nobody is worth it for gameplay IMO. I never intentionally go beyond NP1 for SSRs myself so I'm not going to answer the poll, but I'd say only your absolute favorite would be the answer

I disagree, Bricha-chin~. Having NP 5 SSR is a great thing to have in gameplay perspective~. That way, you can be a Little loose with setup and can easily make various setup without sacrificing much damage~.

It depends on what you value. A lot of people would greatly value them. I personally have no need for any multi NP level SSRs, so the only advice I can suggest is going for absolute favorites. I'd much rather comfortably obtain all of my future targets than get one (or none with horrible luck) at NP5. Not to mention with 90++ existing there's no true omnifarmers that can clear all 90++ nodes or universal DPS to beat all bosses regardless of NP levels or grails.

See, that's where having NP 5 is beneficial~. I can 3T farm the 90++ farming node at Saber Karna event last year with only 1 Altria Caster~. I used both Kama and Summer Kama, and both of them are NP 5, level 120~. So surely, NP 5 SSR can do things better than getting your targets~

I have a NP4 of Morgan and NP4 of Melusine.. I use morgan a lot more than Melusine since she is easier to farm with due to her break charges. But Melusine can run BG and other 0 charge event CEs. So they have their benefits. I have used Arjuna as well and am not a fan of how old he feels compared to Morgan. Kama is good but her ST nature as well as Assassin class limits her DPS. I only have her NP2 though. Other 2 are new units with me having heard good stuff about Berserker castoria but not so much about the count.

So overall I would say:

If you are looking at DMG potential(for High difficulty content like Super recollection/90++): Melusine > Berserker Castoria > Morgan > AA > Kama

If farming: Morgan > Melusine> Berserker Castoria > AA

I have never used Kama for farming as of yet even in 90++. Don't know abt count so not rating him.

I do want to say that Morgan, Melusine, Berserker Castoria are all good enough to be worth NP5 if you like them. Otherwise investing in an NP5 might not be worth. It might be better to grab 2 of them at NP3/NP2 or similar. Depends on your gacha luck since out pity system is garbage.

For reference it took me 1500ish SQ for Morgan to get NP3 + 1 from Destiny GSSR and 1300ishSQ for Melusine but I got her first copy in 16tix on her OG banner so I was lucky on that.

Before getting multi-pity (which we will get next year at the latest), going for more than NP1 (all the more 5) needs an insane amount of luck, since you may get a servant with one roll, but you may as well spend 600$ worth of SQ and get nothing.

As for, if you NEED higher NP levels, that entirely depends.

Take buster AoE. NP1 means 300% base damage. NP2 upps that by another 100%, NP3 by 50%, after that 25% and 25%. In that regard, going beyond 2 is not worth it.

However, you need NP3 to be able to level to 120 with a reasonably attainable bond level (6) and NP2 allows overcharging, which helps to stay on top of NP draining enemies like ghosts.

I personally never actively went beyond NP2 on a single banner for an SSR, but instead waited for a rerun, if I wanted another copy (though there were instances, where I got more than two copies, while trying to get the SR; in fact trying to get NP5 Gorgon kinda scarred me and greatly reduced my expectations on gatcha luck).

None of this answers the original question, though 😉

The diminishing returns after NP3 of a servant mean you should only NP5 if you really want the coins and the servant has a legitimate use for many coins outside of 120 since NP3 already gets you to 120 with a few bond levels. If you really, really, REALLY like a servant that much though go for NP5 out of love.

IDK how you picked these 6 since arguably the best servant to NP5 is Ciel. Her kit is that good and she doubles as a single target and AoE servant in one package.

Out of the ones you listed I picked Castoria summer though because if you NP5 her it isn't an exaggeration that you may never need another NP5 single target SSR ever since the only thing she can't handle is foreigners, however, even against foreigners she can suffice because of her bonus damage against specific enemy traits and alignment and such. While NP5 Melusine is really good don't get me wrong there are saber enemies that stop her from omnifarming 90++ nodes.

Quick edit: to NP5 it usually takes around 1800 SQ and equivalents since tickets count as 3 quartz. Your mileage can vary greatly since I NP5'ed Arcueid for about 1K SQ.

My current savings where 214SQs i'll expect to reach 900SQs till 8th Anniversary for Melusine Ruler obviously i don't mind have her np1 SSR i just predicting i might get her on pity. well honestly is quite unpredictable but i recommend save atleast 1000k or above but i do heard someone got a SSR unit np5 after spending atleast 600 or 900SQs, in rare occurance someone np5 a ssr unit at least 150+ or 200+.

Chances were depending of the banners itself

Since if you save more than 1000+ you can possibly get np5 sometimes 1000 SQs are not enough to NP5 a SSR unit. so good luck

I got a few np5+ 5*, and from experience, I feel safe with something like 2000 quartz. However, the only servant I actually NP5 (6, actually) on their first banner was Archetype Earth, and I got the copies in something like 1500 quartz. My others were on separate banners, with my luckiest one being maybe Tama Lancer, whom I got to NP5 in something like 900 quartz in total, since I remember getting my first two copies in 19 tickets back in year one.

As others pointed out, NP levels beyond 1 have diminishing returns, so I'd only really go for it for love anyway. NP2 is good enough, and I most 5* servants I like are at NP2, only a select few do I have at NP5. Also, I haven't really played any of those servants regularly except for Mélusine, so with absolutely no bias, I'd go for Mélusine haha.