Should I Grail Siegfried?

Gameplay wise, no. Just raise his third skill, he is gucci. Grail for love, honestly. There are only few servants that benefit from grails anyway.

yes,grail it! at least you statisfied as 1st person who grail it

Siegfried is shit as you know he had rank E of luck~

Really just grail whoever you want to. Even if the servant is not as strong as other as long as you feel like you want to then why not. Plus Sumanai gets to be okayy later on.

It seems that you're asking this just based on the fact that Siegfried is a high level gold saber, rather than out of particularly liking him. In that case, definitely no, save your grails. Even if you manage to get a great servant gameplay wise, if you don't like them, don't grail. Save grails for characters you like, since the investment is extremely expensive (grails are really rare and ascension, especially for 4* or 5* can cost all of your QP unless you literally have hundreds of millions of QP). Save until you get Mordred or whomever you really love. Good luck getting a favorite character!

I like him. Works well with Jalter and has a solid set of strengthening quests coming to NA. Bit of a tanky guy too, 12th highest hp in the game! Do it!!