I shall request guidance

I reach my first Billion coins in a run after doing some researching for DW/GT/BH and boosted my waves by almost 2k and im still aiming for more research before playing with builds but i want suggestions for income

I heard i should farm tier 1 so that i can keep my research at least 1.5x which i do but im wondering if i should try going tier 2 at this point but also read that protector can be a pain and i would like to know how much and if there is ways to counter them or smth

Thanks for the help