Practical Sailor had a very good review of liferafts, including their features, advices on what to look for, and which companies promised, but didn't deliver: Life Rafts: The Good, The Bad and The Ugly - Practical Sailor Article
With a newer update here: Life Rafts - Practical Sailor Article
Most companies came out with new models since the times of these articles, but these articles still provide a very good first step.
We don't have a PS subscription any more, otherwise I could've sent you the pages :\
Yachting Monthly also did some liferaft
tests and they have a video on their website: Six ISO 9650 liferafts tested | Yachting Gear Test Videos | Yachting Monthly
If I were you, I would make sure that whatever liferaft
you'd choose was built to ISO standards - gives you better assurance of liferaft quality.