As a for what it is worth:

You say this is your second road bike, so you may have an idea of whether you would appreciate having 10 speeds vs 8. With 10, you can get smaller gaps between cogs, so you can more easily optimize cadence, if you like to optimize cadence. If you rarely shift, or don't mind the current gaps in your 8 speed, then it is probably not worth it.

Since this is entirely subjective, I notice the difference between 8 speed and 9 or 10 speed, but don't notice the difference between 9 and 10, if that makes sense. So 9 is my minimum, and actually preferred setup. But again, totally subjective.

Isn't Claris a fairly new product, like just in the last year? If you don't mind the cog increments, but don't like the shifting or braking action, just install new good quality cables. I just built a bike with a new Sora group, took time and effort with good cables, and the bike works flawlessly.