Guide 5

A quintessential "pipelining" level in my opinion. Dry, exceedingly logical, but requires a decent amount of effort to actually understand why the solution is shortest.

Edit: 3 distinct classes of solutions, each with small timing variations.

Guide 5.5

Circular Saw

Surprisingly logical and uncursed. I do like that every side of the square gives a slightly different variation, just to keep you on your toes.

Pizza Arc Reactor

Sea Stack

HIs mind

As annoying as this can be to solve, at least the solution is pleasantly uncursed.

Goliard

Classic X6

Choices

Vanilla Extract II

An excellent level for sure, but overshadowed by the sheer magnificent brilliance of its other pair.