Make a confident furniture comparison by using the same small set of criteria for every shortlisted product. Start with cat fit: usable resting space, entrances, access between levels and documented capacities. Then compare room fit, cleaning requirements, assembly and any necessary fixings. Finally, consider appearance, price and optional features. Record missing information explicitly instead of replacing it with a favourable assumption. Ask the seller for clarification where a missing detail could change the decision.
Use measurements in consistent units and check that descriptions refer to the same variant. Photos can support the comparison, but perspective makes them a poor substitute for dimensions. The aim is not to create a complicated score that hides judgement. It is to make the important trade-offs visible, so you can explain why one model fits your cat and home better even if another has more features or a lower headline price.
Give each product the same columns in your notes and leave unknown figures blank. A blank internal-bed measurement is more useful than an estimated number from a photograph because it identifies exactly what to ask before choosing.
For product comparisons alongside this advice, see Ultimate PawHouse and Taj-MeowHall. The details below explain their sizes and uses.
Further reading: giantpaws.co.uk.
Ultimate PawHouse
Taj-MeowHall
Cat-Cave