I have Buldar and Azlar @3-70 and Grazul is a week or so from 3-70. I have 10 rings and 359 Barbian emblems. I am try to figure out with one get the rings. I know it depends so here is the depends.
Mitsuko +18 & +3, Marjana +18, Zim+11, Anzogh, Khagan, Wilber+20 and 3 c-BT’s, +20,+18 and 4-70.
Grazul, because she heals and blocks ailments at v. fast speed. She’s a strong offensive support hero.
Azlar would be my 2nd choice because he hits hard even if he’s slow. Good match damage and skill damage, and his burn is great – but maybe I’m biased since I use him with a red ninja troop and makes his burn very powerful.
I didn’t really like Baldur in Beta. The best part about him is the protection against mana reductions – something that is handy in Vanaheim Hard difficulty, against those heroes and against Neith, Guinevere, etc. It’s a bit niche in this meta but it’s notable. That aside, he’s just too passive for me to really consider.
Grazul helps the team a lot at a very fast mana speed. Just a level 11 mana tropp get her firing with 6 tiles or 3 ghost tiles. Once you time her special, it’s one of the most useful tools in the game. I’d even ascend her over a costumed Azlar.
I think Grazul will be best for your red team to increase survivability and ultimately increase win percentage. Try to have a lvl23+ mana troop for Mitsuko and a lvl 11+ for Grazul.