I see Armstrong as an over-excited puppy, constantly affectionate and wanting attention. Roy Mustang is like the coolest black cat ever... sleek, sexy, and oh-so-superior. Havoc is a peacock, strutting and trying to get the ladies. Fuery is a cute rabbit. Falman is a tortoise, apparently slow in action but every move is well-planned. Breda is a mountain cat: you think he isn't as much of a threat as he really is. Hawkeye... well, that's obvious.
Al is a purring kitten, some kind of tabby, I expect. Whereas Trisha was a long-haired Persian or Angora cat. Hohenheim was the phoenix, out-living nearly everyone else. But Ed... I'm not so sure.