Skill wise Nagaraja isn't the best you can get but they do have their use when you need to build your team to take on some harder stages plus her stats maxed are pretty high compared to others, I'll use Oda Nobunaga (Godified) as an example as most people will have her:
Nagaraja
HP = 8373
Attack = 2265
Defense = 2257
Speed =2697
Oda (Godified)
HP = 7611
Attack = 2210
Defense = 2224
Speed = 2868
Now stats aren't everything I know and I don't have Wadatsumi yet so can't really comment on her but I have Kirin and she has some pretty good skills and effect and have also heard she is pretty good maxed stats. Kirin's leadership skill is to protect from paralysis.
Her two skills are
'Divine Light Blase = Light attack 126% on all targets with a high chance to reduce 30% speed'
'Sacred Beast's Blessing = Applies 15% damage reduction to all allies for 3 hits'
Special Ability is Flood Ward
Shes not a bad unit in my opinion.