I found the plastic models like the E red would not read the same on teh same cell twice in a row.
I like the OTC 4619 but one needs to ensure there are no bubbles sticking to the float, and to wait several more seconds to let the thermometer feel the electrolyte temperature so one can add or subtact according to what it says.
Generally cells in the middle after charging will be hotter than those on the ends.
The glass float is fragile, Keep the packaging it is shippe in for storage, and rinse it after each use.
If you get an EZ red, they make nice doorstops.
