Whatever the hell people think they look like, personally, I think they both resemble some bad*** chickens.
Anyway, Zekrom has a lot of Palkia in its legs, though they both have similar legs, his frontal area has those lines that remind me a lot about Palkia.
Reshiram reminds me of Lugia with its pure white, and hands on the wings, having said that, Zekrom's square-tipped wing pattern slightly resemble's Ho-oh's square-tipped feathers.
Reshiram looks more spiritual, and divine, what with the whispy, smoky-looking tail and "hair" as well as its rings. Just makes me think divinity ya'know.
Zekrom looks more of a war and battle kind of dude, with that armor and bad*** jaw
So yeah, reguardless of what they may resemble, or may have borrowed from, they still look awesome, and I'm excited about this game even more now. I can't wait to do some fan-art :3