I had Tektro calipers on my first bike. People said pads will make more of a difference than calipers, so I did a test.
Swapped in 105 pads to Tektro calipers and braking improved greatly. Swapped calipers on bike to the 105’s but with Tektro pads. Braking actually improved again. Then 105 calipers and 105 pads. Yup. Braking was much better again.
My experience showed that calipers were a better upgrade than pads when moving from the basic Tektro.
Tektro do make some good calipers mind you, just not the basic ones that come with most bikes.