I started with Chaos Dwarfs, I really liked Chaos Dwarfs due to initial appeal of mostly appearance. When I was 6 I would play with my dads talisman 3rd editions miniatures and to a kid the huge cartoonish hat, tusks and nose were great on that miniature. Also the plumpness of Warhammer Dwarfs made little kid me love them.
I switched to Empire mostly due to wanting a break from painting Chaos Dwarfs, but now I have gotten really into the Empire. What made me pick it initially was the cool looks, the historical inspiration and the nice characters and lore made for it.
Now I have fallen in love with this faction. The whole Faith, Steel and Gunpowder thing really appeals to me. I love the fact it has no upper hand, not the magics of the undead, the dark omnipresence of chaos, the numbers of the skaven, the technology and stubbornness of the dwarfs, the size of the ogres or anything else. The Empire has nothing special, its Renaissance Europe placed into a world of Demons and Magic. It's amazing how even with no special cards to play it thrives in a world it doesn't belong in. It's carved its place with pure willpower and nothing else.
I love when the Empire is just Europe. I dislike the Celestial Hurricanum and Luminark, I don't like the idea of a griffon leading an imperial army, impressive lords like Valten feel out of place.
The best part to me is it doesn't have any upper hand, other than strategy and will to survive. It shouldn't have big or impressive things. The Theme of the faction is the impressive part. I hate humans in fantasy if they are done like Basilea in KoW. Humans in fantasy should always feel weaker, even Lotr humans are barely holding on. The Empire requires a lot of thinking to win or survive. Which I love.
Another thing I love about the Empire is it's variety, as the 4th edition WHFB Empire book said, "Its the perfect Army for a Master Tactician". Which is true. You can do anything, you can have a balanced force, an all cav rush or a gunline. I love the ability to be able to do so much with my army.
Came for the looks, stayed for the theme and tabletop play.