About Jalter

Go for Cu Alter (stong & self-sufficient servant) if you don't want to bother yourself with team composition to suit Jalter. She is powerful but needs a lot of investement to unlock her full potential.

As someone who's decided to roll hard for Jalter and a relatively new F2P player, I can at least describe my thought process. First and foremost, I personally lack an all-around reasonably durable damage dealer. Heracles is excellent at dealing damage, but as I lack the Hearts to get him to his third ascension, he doesn't have the durability that I need and fits more as a "last stand" backline backup carry than a mainline damage dealer. My Lalter is stuck in a similar situation. As the next event is the Jalter event anyway, it would be most efficient to just wait until then to farm mats, so I might as well roll for one of the better general damage carries in the game before committing to a hard grind. On top of that, I got very lucky and rolled Waver early on and while I still struggle with Star Generation, I have a reasonably well upgraded Hans and Hassan who can function decently well in that role.

Her biggest competitor at the moment is Cu Alter, who, like Herc, is an excellent backline damage dealer. Since Herc fills that spot for me, I don't see much of a reason to roll for him, even if he is generally better. If you have a good mainline damage dealer and want a backline glass cannon survivalist to finish off those bosses, you really can't go wrong with rolling for Cuzilla.

At the same time, my personal reason for rolling Jalter is also that she has an excellent design and I love her aesthetically, combined with my general enjoyment of Alter characters in general, so I have Waifu reasons as well. All in all, it's your choice on who to roll for and I hope your rolls are favorable.

Roll for waifu, my friend
If you love her, go for her
Don't make reviews stop you from getting the servants you love

Jalter should still do fine, even without the expensive supports. She does require Merlin to become 'broken', but even without Merlin/Waver you can always use other supports. If you're going for both gameplay and personal preference, I would argue that she's still worth it. As a standalone unit, there will be better ones of course but she's far from bad without the 5* support units :)

How about Angra Mainyu?

Go with this comp.
Jalter (Buster/Crit CE) -Hans (2030) -Support Nightingale/Waver (2030)
Hans and a couple of 2030 will provide decent count of stars when you need them. This will also work if you don't have your own 2030, but less consistent. Of course, as per every team comp, you need to max level every required skills for max effectiveness.