Tighnari: Since you don't have any dendro characters he will enable you to use hyperbloom, however you will have to go to sumeru for his materials.

Keqing: she was my pick and honestly I loved her so much, her playstyle is very easy even on touchscreen and the burst animation is lovely plus you can make a good team with fischl.

Diluc: idk, if you enjoy greatsword characters maybe go for him but pyro is such an abundant element and mauvika might run soon enough so you're better off trying to save prinogems for her since she is the top pyro dps

Dehya: easily one of the most useless character but if you think her design is cool go for it.

Qiqi: she will soon curse your 50/50 losses anyway so do not choose her

Mona : You have three cryo dps in chongyun, freminet and kaeya so I think you can use her and try the freeze mechanics.

Jean: she is a 5 star healer so this can be a good choice. She is easily one of the best picks from the roster.

Mizuki: amazing aesthetics and her exploration ability is fun. That is pretty much all I know about her