Who to save for aside from Merlin

U have King Hassan on early january, which in my opinion is one of the best SSR assassins of the game.

For lancers, sry but i dont have intel for that. Just try to aim for enkidu i guess?

Here's a list of all of the JP banners that we may or may not get from now to next year. If you're looking for great lancers, you're probably looking for Summer Raikou and Brynhildr (Looks like she's in next year's Nerofest), who I heard are some of the best Lancers.

https://grandorder.wiki/Upcoming_Summoning_Campaigns_(for_EN_reference)

King Hassan I believe is supposed to come out the beginning of next year and is consider to be an op Buster assassin, he also has a ST np making him great for boss fights, so there’s him to look forward to.
Enkidu should come out with one of the Babylonia chapter banners and they are considered to be a good ST lancer, though it seems they are more quick based. On the top of lancers Artoria Lancer should have another rate up banner along with the Knights of the Round Table if you want to try for her instead, she is an AOE lancer in comparison to Enkidu though so decide which one you value most.(Keep in mind though that this isn’t a solo banner and that Artoria Lancer is there with her regular saber counterpart so your best bet at getting a lancer is gonna be with Enkidu).
Musashi is often considered to also be one of the best buster based ST sabers and she’s coming around the same time as Merlin as one of the servants under the new year’s summoning campaign. Some notable servants on rate up as well for this banner are Ishtar, Scathach, and Gilgamesh.
Ishtar is also gonna be getting her own rate up as well. Top notch damage dealing AOE archer and is a Pseudo servant using Rin Tohsaka’s body. What more could you want?
Lastly Quetzalcoatl is a ST rider on par with Ozymandias and is also Buster based. She’ll get her rate up as one of the Babylonia chapter banners.
All these servants are definitely worth considering, of course one can’t have all of them so you’d probably have to do more research and decide for yourself which ones you want. Anyways hope this helped.

There's no one coming out soon who possesses the sheer utility of Waver and Merlin. Caster Scathach is probably the next best one but we aren't gonna get her for a long time.

The best gold lancer that's coming out is probably Parvati
, who has a targetable NP charge, as well as charging all allies NP gauge during her own NP.

If any gold lancer will do, vlad extra is coming up.

Merlin is coming as early as late November since we're not exactly 2 years behind JP, and defo a servant to splurge on. No trashy 2nd servant rate up, it's Merlin only for the entire campaign. Merlin only ever got a 2nd summoning campaign on JP and the rest are lucky bag draws. Aaaand he's limited too...

As I'd say the more SQ you save, the more salt when you don't get the servant. You'd have to average 429 SQ to get the rate up SSR on a single SSR rate up, anything under that you can consider yourself to have beaten RNGesus.