I mean
I think a decent server would be a removal of the cash shop but keeping those 3-4 $9.99 monthly packages to help with server costs.
See I think best method would be keeping the shop with Gold that can be used to buy and sell things both in the store and market but the actual shop itself to consist of only Cosmetics, Mounts, Extension tickets, PVP buffs, PVP Healing potions, and PVE Buffs. With special 1 time level packs being revamped with resonable ticket.
Then Having a F2P Season pass, a £5 worth of gold and £10 of gold one so thats £15 a month to earn a lot of resouces which imo is fair and resonable the other stuff in the shop doesn't directly effect power to a large extent.
Then I would add Ticket boxs as a rare drop to SP/MS none summon item bosses, Spirit tickets to Valley subs, Skill tickets to Elite field subs, Material tickets to Lab subs extremely rare and not box's just single tickets.
Revamp bosses to drop good loot making them worth fighting over and arguing over who takes what chests in clans.
Bare in mind if you make it so gold instead of cash is used for seasonpass purchases too it then becomes a hard tradeable currency within the game and even fully f2p may be able to sell items for Codex, magic stones, etc to cover them fees each month and compete and the things they would be selling will give an edge to those who don't really mind spending.
Basically make a server that you get out what you put into it in effort instead of who has the biggest bank account, Ya know the way games should work.