Here are the top online booking platforms by category, why they’re good, and when to use each one — plus quick tips to get the best price or protection.

Flights / flight search

• Google Flights — Best fast search, great calendar view and price-change tracking; excellent for exploring dates/routes. (time.com)
• Skyscanner — Broad search across airlines/OTAs, whole-month view and strong for finding the cheapest carriers or third‑party fares. (travelwise24.com)
• Kayak / Momondo — Meta-searchers that compare many sites and sometimes surface the lowest fares (Momondo often finds very cheap fares). Use them to cross-check prices. (travelwise24.com) When to use: start with Google Flights for route planning + Skyscanner or Kayak to verify the best price. If you find a low fare on an OTA, confirm the fare on the airline site before booking.

Hotels / packaged trips

• Booking.com — Huge inventory worldwide, flexible free‑cancellation options on many properties, easy filters for family/business stays. Good for hotels and some rentals. (forbes.com)
• Expedia / Hotels.com (OneKey family) — Good for bundle discounts (flight+hotel+car) and loyalty credits; shows final prices clearly. (forbes.com)
• Google Hotels / Trivago — Great for fast price comparisons across booking sites; use to spot lowest-listed rates. (forbes.com) When to use: compare Booking/Expedia/Google for the final price (taxes/fees) and check the hotel’s direct site — sometimes direct booking gives perks or easier changes.

Vacation rentals (homes, cottages, condos)

• Airbnb — Largest inventory and strong UX for shorter, unique stays and hosts with reviews; good filters and guest protections.
• Vrbo — Best for whole‑home stays and larger-group rentals (more traditional vacation-home inventory). (tomsguide.com)
• Aggregators (HomeToGo / Tripping.com) — Useful to search many rental platforms at once (find listings that might be otherwise missed). (en.wikipedia.org) When to use: choose Airbnb for unique or host‑shared experiences and Vrbo for whole-house family/group stays; always read cancellation rules and cleaning/fee breakdowns carefully.

Meta-search / aggregator tools (best for comparing everything)

• Kayak, Trivago, Skyscanner, Google Flights/Hotels — Use these to compare results across direct sites and OTAs quickly. They often redirect to the merchant to complete booking. (travelwise24.com)

Specialized/niche options

• Hopper — Price prediction and alerts for flights (and some hotel deals); useful if you can wait for a buy window.
• Agoda — Strong in Asia and for hotels in that region (often competitive rates). (en.wikipedia.org)

Practical tips (to save money and avoid problems)

• Always compare at least 2–3 sites (meta-search + direct). Meta‑search can find the deal, but confirm on the airline/hotel site for warranty and easier changes. (time.com)
• Watch final price (taxes, cleaning fees, service fees). Some rental sites add large cleaning/service fees at checkout. (tomsguide.com)
• Use flexible-date calendars and price alerts to catch dips. (travelwise24.com)
• For big spends (international trips, big group rentals) consider travel insurance and pick platforms with clear support/contact options.
• Be cautious of look‑alike/“copycat” booking sites; prefer well‑known platforms or confirmed hotel/airline pages. (wsj.com)

If you want, I can:

• Narrow this to your exact trip (dates/destination/budget) and run live comparisons, or
• Give a short checklist to compare any two specific sites you’re deciding between.