Depends on what you need, but I would probably go with Iceman as a generic recommendation.
Normally, I believe you should rank up for two reasons. One: you are filling a need. Two: your catalysts are in overflow and about to expire.
Your first 5/50 should fill some need, or benefit you in some way beyond just having a 5/50. You have a questing team you are using to do single player content like the monthly events. You may have an AQ attack team and an AW attack team. Do you need more damage, do you need a sustainable healing champion, do you need a boss killer? Maybe you run lanes where immunities and power control would help, and Vision is the best choice. Maybe you need something that can defeat very strong boss-level champions, and Iceman would be a good choice. Maybe you need a high damage dealer and Medusa would fit the bill.
The last time you couldn't complete some content, or you died and had to revive, or you had to buy or use potions, what would have helped you out there? That's where I would look to decide what to rank up.
Comments
Normally, I believe you should rank up for two reasons. One: you are filling a need. Two: your catalysts are in overflow and about to expire.
Your first 5/50 should fill some need, or benefit you in some way beyond just having a 5/50. You have a questing team you are using to do single player content like the monthly events. You may have an AQ attack team and an AW attack team. Do you need more damage, do you need a sustainable healing champion, do you need a boss killer? Maybe you run lanes where immunities and power control would help, and Vision is the best choice. Maybe you need something that can defeat very strong boss-level champions, and Iceman would be a good choice. Maybe you need a high damage dealer and Medusa would fit the bill.
The last time you couldn't complete some content, or you died and had to revive, or you had to buy or use potions, what would have helped you out there? That's where I would look to decide what to rank up.