Without question, Forgotten Ancient. Generically, it's above and beyond better.

Is your ramp good? Do you need color fixing? No? Then Ancient.

River Kelpie could be a niche case but the easiest thing to bring back are creatures.

What about one time effects like Mulldrifter or Baleful Strix?

Also, would you count a tribal restriction? Such as when you cast X (Knight, Sliver, etc.), draw a card?

I know you have a maybe board but if you consider there are also artifact, enchantment, and land creatures, then your maybe board could get a bit large.

I would point out, that at least in commander, basic land tutors such as Rampant Growth tend to be benign. Players may notice excessive ramping but rarely get upset at the tutoring itself.

Personally, I think tutors (outside above mentioned) make my decks less fun to play. I'd rather include another good card than a tutor. Even my combo deck has minimal tutors and prefers to rely on card draw. Decks that play too consistently (looking at you Relentless Rats deck), even when not good, get boring to play quickly in a casual setting.

I'd say redundancy is good but the crawler and fertalid are also sufficiently different. Crawler stores mana and fertalid ramps out basics. There accomplishing the same goal but differently. Though, generally ramping lands is better both for thinning and resiliency. Keep both.

You should find room for the ancient, it's just too good (unless you want less efficient). Start looking at 5cmc creatures then if unwilling to cut, take a look at your sorceries and artifacts starting at high cmc and going down.

Crystalline Crawler works as a good battery for both counters and mana. I'd go that route over the Automaton if your removal is already good.