I agree that the Sandy Bridge era (2011) ThinkPads were the last to have a proper 7 row keyboard layout, but there's slightly more to it.
ThinkPad keyboards are made by a variety of OEMs. For the 2011 models, the manufacturers were NMB, Chicony and Alps. The consensus within the ThinkPad enthusiast community is that keyboards from NMB offered the best typing feel, followed Chicony and finally Alps.
You can tell if you have a NMB keyboard by carefully prising off one of the keycaps: if you see a red rubber dome, it's a NMB keyboard. (grey = Chicony; white = Alps). Each keyboard manufacturer has a unique part number (FRU - field replaceable unit in the IBM/Lenovo parlance). Online sellers often mix and match FRUs, so it can't be relied upon to get the NMB keyboard - you need to ask the seller what colour the domes are. The NMB keyboards are sadly becoming more rare and expensive by the day.
FWIW, chiclet machines often had better feel than the 7-row predecessors. E.g. T440p with non-backlit keyboard. This is due to improvements in chassis design - the T440p's magnesium alloy rollcage was solid underneath the keyboard, resulting in 0 keyboard flex.