3 GB is decent as a baseline, and I just bought an iPad 7 with 3 GB RAM, but it's unfortunate they didn't pair the speedy A12 with 4 GB RAM, esp. since it directly replaced the iPad Pro 10.5" with 4 GB RAM.
In my experience, at least for general usage, the amount of RAM is more of a bottleneck than the CPU if the CPU is a decent one, and both A10X and A12 are very decent.
I do also really appreciate the quad speakers on the iPad Pro, even though I only use them occasionally. Our iPad 7 also has just two speakers, and it reminded me just much I hate having the sound coming out of only one side in landscape mode. (I have Apple Smart Keyboard for both the iPad Pro 10.5" and iPad 7, and that's generally how we use them on the table.)