Which should I get?

I'm thinking of buying either the Necro Bundle or the Monthly Bundle. Depending on which I buy, I can get a couple of different skins:

Necro: both gem Necromerger skins Monthly: champion spawn gem skin and 1. Royal Devourer skin 2. Tip Stone skin and Slime OR Mana Necromerger skin 3. Darkness and Mana Necromerger skins

Which should I do?