Trane coil vs Aspen coil

We had a A/C technician come to our house to put in more freon. He told us that the evaperator coils for both units (8 years old, 3.5 and 4 tonnes, Lennox) need a replacement (I don't know how he determine this since I was not at home). He would like to replace the existing coils with Trane coils. The cost is $1200 each.
We had another A/C technician come out and he would like to replace the
existing coil with Aspen coil. The cost is $850 each.
Can you please tell us if it's better deal to go with the cheaper solution? How much better TRANE vs ASPEN coil that justifies the cost?
Also, how do these people know that the evaperator needs a replacement?
I wasn't at home when the first technician was here but the second technician doesn't measuring anything to indicates that the evaperator is the issue.
in addition to the repair/replace question, some other questions:
1. Do the prices seem reasonable? 2. Is repairing the coil leak a reasonable option?
Thank you
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