How to tell a band member that you really dislike something they wrote?

I have this problem with my bro sometimes , we're both guitarists , I remember a while back he'd get all pissed if I said I didn't like something he wrote. But these days I'll just write something that I feel fits the part better and present it to him , and he will usually agree it's better.
 
The average band has 4 members. If 3 of those members dislike a riff, that's a 75% disapproval rate. If the same ratio of your listeners don't like the riff, you'll lose them.
Definitely have to step away from the material that you contribute individually to stay objective. Keep the throwaway riffs for solo projects or Japan-only singles.
 
In my opinion, the other guitarist writes stuff that would seem more appealing to a mainstream audience. This is where I get my panties in a bunch. I don't want to appeal to that type of crowd, as much as it'd help us out.....I want to keep it metal and appeal to the headbangers and fist pumpers and not venture into 'mainstream'/sellout type of territory. If this makes any sense.

We've also been having a hell of a time trying to track/edit drums. Just when we were "done" editing drums, last night, come to find they tracked a part withOUT the click....while I wasnt there....and it was off in 2 spots, and they couldnt seem to fix it....dude recording us didnt seem to take any of my input about pasting in kick hits and time stretching the OHs so it fits right, and is saying we need to retrack. Getting tired of the run-around, really.