TL;DR. Two budget hotel cobrands. Wyndham Earner Plus ($75) earns 6x on Wyndham, 4x on gas and groceries, includes 7,500 anniversary points (~$75 value) and Platinum status. IHG Traveler ($0) earns 17x on IHG, 3x on gas and dining, and includes the fourth-night-free award benefit. IHG Traveler wins on fee and breadth of stays. Wyndham wins for the niche use case of Vacasa rentals and Caesars properties (which take Wyndham points).
The three dimensions that actually decide it. First, fee. IHG is $0; Wyndham is $75. Free card vs paid. Second, footprint. IHG includes Holiday Inn, Crowne Plaza, Kimpton, InterContinental (~6,000 hotels worldwide). Wyndham includes Wyndham brands plus Vacasa vacation rentals and Caesars properties (unique). Third, redemption density. IHG's fourth-night-free works on any award stay. Wyndham points redeem at flat 15k or 30k a night, which can be a steal for high-cash-price hotels.
Real customer scenario for each. If you stay at midmarket hotels for short trips, IHG Traveler's $0 fee and fourth-night-free is the obvious choice. If instead you book Vacasa rentals or Caesars Las Vegas stays, Wyndham Earner Plus is the only card that converts those into points-paid stays at the 15k-30k flat redemption.
The trap to avoid. Holding Wyndham Earner Plus for the Platinum status without actually using it. Wyndham Platinum's benefits (late checkout, 15% bonus) are modest compared to Marriott or Hyatt elite. The card's real value is the 15k-30k flat redemption ceiling at high-cash-rate properties.