Currently on my team are:
Saber: Gawain,Gaius Julius Caesar.
Assassin: Emiya, Fuuma Kotarou.
Caster: Merlin, Medea, Hans.
Lancer: Cu Prototype, Santa alter.
Rider: Santa alter, Saint Martha.
Archer: Emiya, Robin.
Berseker: Kiyohime.
Extra: Jeane
¨¨¿What would be the best option to front the current weaknesses of my composition?
lancer/saber/berserker and probably rider are the best choices
But i would say go either with berserker or lancer since they have the best servants but saber are still a valid option.
If you want a st rider then you have 50% of getting either ozy or quetz and they're both very good
If you want to play it safe go with lancer(karna and arthuria are very good aoe servants and enkidu is a really good st lancer)
1. Roll for your favorite.
2. See your weakest class on each department.
3. Gamepress tierlist is one of the best way as a guide or something that can help you decide it, at least from the gameplay standpoint.
4. It doesn't have the servant that you don't want.
I'm repeating one of the good point said by Omrus and i'm pretty much agreed with this options.
Option 2 and 3 is a good choice for you, roll for Berserker banner.
Not going to particularly advise you, but I've got the same Caster roster as you and I'm going to pick caster as I would be happy to pick up Waver even with a Merlin, as I see their niches being different. Plus, I wouldn't mind a Tamano, or even a Sanzang when I want a strong (well, stronger) DPS out of a caster--Medea I found is fine up to the point where an Assassin target has about 40-50k health, but after that, she can't OHK with her NP alone and that makes her less attractive.
Sabers: they're all aoe. Gwain has you covered.
Assassin: Jack and risking an np2 jeanne. I wouldn't go for it
Caster: Waver is a great np charging battery. Tamamo for arts team and titty monk is a decent single target but she's a caster(0.9 mulitplier). Lu bu hits harder for your single target nping needs. I wouldn't go for this unless you really want Waver.
Lancer: I believe they're all aoe. Lancer alter has you covered unless you want np charge which both Artoria and karna have.
Rider: Quertz and Ozzy are amazing single target servants. Drake has an np charge so she's great for aoe farming. Medb is mehh. She's the worse thing you could get here.
Archer: Arunja 25% and Tesla a 50% np charge at Max level. They aren't bad for aoe farming. Orion has a single target male niche which isn't as good as an easily obtainable np5 euryle.
Berseker: Cu alter would be really good for you. Vladd and Nightingale needs set up.
I would go for riders if I were you. They all have buster nps so they go great with your Merlin.
I suggest berserker because quite frankly, Kiyo won't cut it for battles with mixed classes. She is mainly used for farming and is not suited for long fights. I would have said go for Rider/Lancer since those classes currently have the strongest servants to pick from (Caster is always good but you have Merlin so its not a priority).
Berserker class is your weakest so pick Berserker and pray you get Cu Alter. At the end of the day, you should always pick for servants that YOU like. Im personally waifu/husbando > gameplay. Hope this helps. Happy Holidays!
