Raising new servants

Martha should be leveled, bonuses or no. She has party heals and debuff removal, plus she hits pretty hard and has some serious NP gain for spamming. Plus, her Phantasm is a buster AOE and lowers enemy defense, so chaining her with other buster servants can make for some devastating combo attacks and help your party punch a little outside its weight class in some cases.

TLDR: Martha is an awesome support that'll make your high level servants hit much harder and survive just a little longer, even if she's only moderately leveled.

To correct the record, Martha does not hit hard at all. Her NP gain is decent though I guess.

Not too much event bonus for these three servants in the near one year. Only Valetine.

In recent, Lancelot>Martha>Marie. In future, Martha>Lancelot>Marie.

Leveling Lancelot, if you have CE to charge his NP, and Waver and taunt unit for support. He is one top servant for farming, and critical damaing after his NP released. But he is a glass cannon. If you dont have any AOE berserkers, then Lancelot is great.

Martha is also excellent due to her unique buff-debuff. Her shinning time is in the future when more and more challenge quest will be presented. However right now she is not easy to use because (1) unnecessary high star adsorption by the rider class, then normally you cannot put her as support for critical team (2) poor attacking, even NP as Buster. (3) 2nd skill team healing is somehow low for HP amount but high cooldown.

Marie is not bad because of her good durability versus male casters. If you dont have other riders, then she could be a good choice. But right now at least you have Kintoki rider as welfare, right?

In addition, leveling Tamamo as first priority if you dont have Shishou or Karna as SSR lancers.
Leveling Nursery as second priory if you have Hans maxed and decent art team.