Holy crap, does anyone around here actually function in a real world? When my band members tell me something they like or dislike about what I am doing, I listen. When they do something I don't like or think is wrong, I tell them. I don't get my undies in a bunch thinking they are all idiots and I am just going to do and play whatever I want. Last time I checked, a band was a team effort and the way the band sounds as a whole is what matters, not your independent opinion that, "that gui**** has no idea what he is talking about and I am just going to do whatever I want."
This.
I was kinda kidding around before (not really- pbasses do sound better IMO), but I would at least check it out. It could be that he wants you to play *his* bass (which makes sense- he probably got his bass because he likes how his bass sounds), or it could be that he has an idea of the sound he wants but might not know the exact way to get there. Either way, letting your pride determine how you act is a recipe for unspoken grudges and discord down the road.
I know that between my friends and I we are always telling each other what gear to get. It is kinda playful, and kinda annoying, but good-spirited. I'll tell him to buy a Badcat amp, he'll tell me to buy a Pbass (which I actually just did. That was something I was very much against at first until I realized that he was right). He'll tell me to buy this pedal, I'll tell him to sell his whatever. He'll say I'll love bridge pickups when I get better at music, I'll tell him he has fallen for various guitar myths that aren't true. It could be half-serious ribbing going on for you, too.
And he could be listening with his eyes, but being disagreeable isn't going to change that or make it better. I'd say give his bass a chance and see if you like it better or not. If you don't, then you have at least shown you have listened and y'all can probably come to an agreeable disagreement, or work and figure out how you can get a tone you both like. And, hey, at least he wants you to be heard.
If y'all are making an album together, than you don't want to ruin it with attitudes.