The one you play the most or that you only don't play because it's not a high enough rank.
There is a race to get 3 different one to rank 4, so whoever you take to R3 you are likely to have to go R4 for Paragon.
Titania and Hulkling are the most widely useful ones of the bunch though, but Titania is already on the 7* pool, so anything over R2 may be regretted if you pull her as 7*.
AvoidedMist
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There is a race to get 3 different one to rank 4, so whoever you take to R3 you are likely to have to go R4 for Paragon.
Titania and Hulkling are the most widely useful ones of the bunch though, but Titania is already on the 7* pool, so anything over R2 may be regretted if you pull her as 7*.