I personally use the Hanna HI96822 digital refractometer.
It is simple and easy to calibrate and has been very consistent. I do warm it up with my hand to 78 degrees prior to calibrating or measuring to ensure that the sample is as accurate as possible.
There is deviation if there is a large temperature difference. This is true with all salinity measuring tools. They all claim to have temperature compensation built in, but beyond a few degrees they start to lose accuracy.
I would not recommend the hand held pen style Hanna salinity tester.
https://premiumaquatics.com/products/hanna-98319-waterproof-salinity-tester.html
It drifts a lot and requires constant recalibration. You also have to use their 35ppt solution to calibrate it which is a consumable item (I have tried to use others and it never "recognizes" them). People seem to love them, but I question how they feel about them after long term use. Works great as a thermometer though.
The "Gold Standard" for me is the Tropic Marin High Precision Hydrometer. Noting to calibrate and it just works every time; just at the cost of ease of use.
Ensure that your equipment is reading correctly and your aquarium is at the right salinity with Tropic Marin's High Precision Hydrometer. Many tank inhabitants are sensitive even to minor changes of the water conditions. Unfortunately as we've all experienced, salinity reading equipment as...
www.bulkreefsupply.com
And the "I'm not just sharing bogus information just to hear myself talk" photo... One is far better than the other.