I like both, in particular the 3a Pro, I am one of those people who really enjoy the massive, maybe even slightly chaotic camera design.
However I have to say the Nothing design team did an amazing job with the 4a, for me I prefer it ever the regular 3a and even the 3a Pro. The design got a bit more busy and detailed around the camera bump, while the lower parts look somewhat cleaner, I enjoy what they created, especially with the new glyph bar. If I wouldn’t own the NP3 already, I would get a 4a for sure.