Hi Joe Cool,
No worries!
While you wouldn’t be able to determine that unless each item was next to each other, based upon the specifications the Tuft & Needle and the Love & Sleep should be quite comparable in both motion transfer and edge “feel”, with the Luxury Firm version of the Lover & Sleep probably feeling a bit firmer on the edge. Both of these brands use similar materials. The T&N might have a bit more “localized bounce” than the Love & Sleep. The Alexander Signature would have more motion deadening characteristics than both of these items, but would probably feel a bit softer on the edge because of the extra memory foam in the upper layers of the mattress.
Overall, memory foam is the best at motion isolation but latex and pocket coils are good for this as well (see post #18 here). Having said that … all the layers and components in a mattress will have some effect on the feel and performance of all the other layers and the mattress “as a whole” so the best way to test for motion isolation is your own careful testing on a mattress using the testing guidelines in the tutorial post (with both of you on the mattress) because a mattress that may be “motion isolating enough” for one couple may not be as suitable for another couple that is more sensitive. Post #4 here also goes into more details about some of the things that impact motion transfer/isolation.
Phoenix