PCMS (Pairs, CMSLL, M and S slices) is a widely unused, somewhat unknown, but very fun columns-first speedsolving method. Its steps are as follows:

  1. Pairs: Solve the four F2L pairs
  2. CMSLL: Solving the four U-layer corners without regards to the M or S slices of the cube. Most if not all algorithms will be identical to CMLL
  3. M and S slices AKA L8E: Using a mixture of intuitive solving and algorithms to solve the remaining 8 edge pieces

The Pairs step isn't too hard, but to get fast at it you need good lookahead and the ability to think outside the box of regular CFOP F2L. CMSLL isn't difficult either, and the speed and length of the 42 algorithms fall somwhere between 2x2 CLL and CMLL.