Team Comp and Potential Thanksgiving Banner Rolls?

In my opinion with merlin you don't need a quick/crit team.
With him you can create a good buster/crit team.
If you still want a quick team maybe an Archer can help you with stars generation

So, I'm going to try to do what others did for me not too long ago.
...
Jack - Solid star generator, and crit master (Definitely frontline material)
Kintoki - A secondary DPS with spam potential (Could act as second to Jack to make a spamming quick/crit team) Note: His rider class will make him soak up a good chunk of stars but, with Jack that's no problem.
Next in the setup depends on the enemy:
Carmilla - With Jack, absolutely destroys female enemies and as a quick servant her only disadvantage would be her buster NP with the other two.
Lancelot or Atlanta: Really for farming with their AOE. But, Lancelot deals great damage outside his NP but, his Buster deck would be a bit of a detriment to Quick teams, but, you star generation's on point either way. Atlanta's first skill is great for boosting quick performance for a turn and is a great support. But, she deals subpar damage overall. They both also have awful NP gain (Less so with their skills but even then it's pretty bad.
Cu should be reserved for solos since he's extremely self-sufficient, a quick team set up won't really help - he's the last man standing type of servant overall.
Cleo is a great assassin farmer but, I don't believe her role as a star generator would help your set up, she's a built-in survivor with a Quick/Buster Deck, whose damage is a bit odd. But, overall with Jack and Kintoki, she should fit in nicely and help clear out waves.
Finally, Marie Antoinette (Rider) is like Cu a survivor type servant, for your needs she's a pretty bad star generator and won't really help with damage, her class would also soak up most the stars. However, in a stall team, she could actually be paired with Cu (Maybe) since they both have a three-hit protection - her Np is also really great for healing the party. She's a self-sufficient survivor, so much like Cu, she probably wouldn't fit.
Honestly, you have enough of an attack line up to be fine, Scathatch would be a cherry on top but, overall you can make do without her. Honestly, go for a Jack/Kintoki/Support set up, you have a great star/NP generation and damage already with those two, so surviving would be all you need.

I have Gilgamesh and pretty much i can tell he make me so lazy not to use another Archers.
My simple team, if there's servants except tough/durable lancers i just put Gil immediately + Hans and Leonidas/Helena or friends Waver.
Vs random saber/berserker enemies, he also still can deal huge damage.

He wreck things so hard at the past Nerofest Grandfinal, i even freaking reset FGO app because he just obliterate almost entire servants there while laughing like crazy.
Nerofest Grandfinals is lvl 90++ node difficulty, so you can imagine how powerful he is.
The result is the fight was really not challenging if i using Gilgamesh.
So in the end, i use my art semi-stall team to clear the grandfinal by not using any Gil.

In the Training Ground nor non-hard events i rarely use him now, i rather give other servants a chance to show up and building their Bond level.
Gilgamesh is a really greedy servant honestly, what kind of servant that can take 3 roles on the same person.
He is just a level below Merlin and Waver, in terms of gamplay and until now still one of the best archer.
He sit at max Bond and i need some QP to max his 2nd and 3rd skill.

Same cases with using friends Tesla, using my Caesar + Helena + Leonidas/D'eon + Hans.
Similiar result just happened like Dejavu while i'm using him at Nerofest, he is more or less Gilgamesh twins in terms of gamplay.

Comparison by Memes :
- Gilgamesh is a freaking Gilgamesh.
- Ishtar is female Gilgamesh with black hair.
- Tesla is Gilgamesh with lightning.