the same can be said of race: I may subjectively prefer white people.

Yes. That's perfectly fine. In fact, if you examine the revealed preferences (e.g. who people prefer to have as their neighbours or who do they prefer to marry) you will see that most people in reality do prefer others of their own race.

And, of course, the same can be said of sex, too. Unless you are an evenhanded bi, you're most certainly guilty of preferring some specific sex (or maybe gender, it varies).

You might bite the bullet here and say that yes, in fact, racism, sexism etc. is morally acceptable

"Morally acceptable" is a judgement, it is conditional on which morality you're using as your standard. Different moralities will produce different moral acceptability for the same actions.

Perhaps you wanted to say "socially acceptable"? In particular, "socially acceptable in contemporary US"? That, of course, is a very different thing.

I think most people would agree that these __isms are wrong, and so speciesism must also be wrong.

Sigh. This is a rationality forum, no? And you're using emotionally charged guilt-by-association arguments? (it's actually designed guilt-by-association since the word "speciesism" was explicitly coined to resemble "racism", etc.).

Warning: HERE BE MIND-KILLERS!