New player what ponies To buy?

Recently started this game again after so long. There's a 80% gem discount on some ponies. Some costing bits. Is there any ponies I should buy or not buy? Ponies I can afford rn Bits : Starlight glimmer & apple jack Gems (Can only afford 1): Trixie Lulamoon , Francesco, Princess Luna royal guard, Nightmare Trixie, Cleopatra Mummy Hearts: Zecora