The angel of darkness vs The Shifting Tide: Which Should You Read?

Both live on shelves: Serial murders, Private investigators, Historical Fiction, Thriller, Mystery, Fiction

The angel of darkness Caleb Carr · 1997 ★★★★☆ 4.1 640 pages · ≈ 11 h 51 m · Light Find on Amazon

The Shifting Tide

The Shifting Tide Anne Perry · 2004 ★★★★☆ 4.2 339 pages · ≈ 6 h 17 m · Moderate Find on Amazon

The verdict

Ratings are close: 4.1 vs 4.2 — either is a safe pick by score.
The Shifting Tide is the quicker read — about 6 hours vs 11 for The angel of darkness.
The angel of darkness is the easier read (Light), The Shifting Tide more demanding (Moderate).