@Savaaage

Paradise Mantle being an Equipment is a significant quality. Mana ramp drawn late isn't great, but a Mantle can still draw a card with Puresteel Paladin and is a cheap, inconsequential way for another creature to have double strike when Halvar  ^Flip is out. The drawback for this synergy is that Mantle is less consistent at mana production. I haven't decided on what Mana Crypt's replacement will be yet. There's plenty of time for discussion.

I had issues with Sigarda's Aid doing nothing for Equipment that's already in play. I could give it another try, but it's not replacing a mana source.

Land Tax isn't a ramp effect, and I don't understand the current appeal of it. Weathered Wayfarer is a much better repeatable land tutor when behind. Claim Jumper closes the gap against Green better. There's also Sword of the Animist and Sword of Hearth and Home to keep pace with the ramp player and gradually build a resource advantage. I see Land Tax as an outdated staple from the old days of the format before most of the new tools came along, and it sticks around largely out of habit and high-profile reprintings drawing fresh attention to it.

@Last_Laugh

I'm sticking with another Mana Rock for Mana Crypt's replacement.