What bike should I get? Really not wanting to regret a purchase.

The White Trek domane is $1,700 and the other is $400. Big difference.

White is 10-speed Shimano Tiagra drivetrain

The Domane ALR 3 description (USED Bike)

Frame: 200 Series Alpha Aluminum with IsoSpeed, 54cm
Fork: Domane carbon fork
Drivetrain: Shimano Sora 9-speed, 50/34 chainrings, 11-28 cassette
Brakes: Tektro T731 with Shimano Sora levers
Tires: Bontrager R1 Hard-Case Lite, 700x28c (tubeless ready wheels)
Saddle: Bontrager Affinity Comp

Known issue: The rear shifter cable may need replacing soon. It occasionally needs a second try to downshift to the smallest cog. Easy ~$40 fix at any bike shop. Priced accordingly.
Otherwise rides great — smooth, fast, and comfortable on pavement.
Perfect for commuting, fitness riding, or someone looking to get into triathlons or road cycling without breaking the bank. No