Titans are the premier choice for this trophy because of their specific faction upgrades: Increases Maximum Mana by 150.
The (Research) or specific Building Upgrades can be toggled. mana matrix realm grinder guide
Watch out for the Well-Read trophy or Research traits that increase mana based on "Total Spells Cast." If your mana is slowly rising while you sit there, you have a scaling upgrade active. Try to finish the trophy quickly before the number moves. Titans are the premier choice for this trophy
If you are at 4,748 or 4,749, check if you have any upgrades that scale with time. Sometimes waiting 10 minutes will naturally tick your mana up to the required 4,750. Conclusion 748 or 4