In general, I recommend the Hero Subscription because it has the fastest TA time and most coins allowed, which overall gives it the highest potential profit making capability. The Adventurer Subscription is second and the Explorer is third as far as maximum profit potential goes.
If you have at least $1000 worth of base currency: Hero Subscription
If you have between $300 - $1000: Adventurer Subscription
If you have less than $300: Explorer Subscription