How can we measure the quality of the FIR filter?
The answer can be given without being at all specific to filters. In fact, one has to answer that in terms of engineering in general:
Whenever you have alternative solutions, the only measure of quality that really matters, is fulfillment of the requirements.
So, you'll have to know what you'll use that filter for, and evaluate how well the alternatives perform with respect to that specific application. Nothing else helps you. There's arbitrarily many properties that a filter can have, and for most of them, it's not clear whether a smaller or bigger value is better, and they all are intrinsically linked to other parameters. There's no single &quot;best&quot; solution, all depends on the application.
So, define your application. Define how that sees performance. For example, if your FIR is used in a wireless communications system, then the FIR that makes the system have the least bit error rate might be the &quot;highest quality&quot; one for this one system under this specific metric that you care about. For a different system, a different FIR will be the best one.