Rubber dome, bleh... I know, I know... but it has to be my MS Natural Keyboard Pro that I have been using since 1999.
Never given me a problem. When spend 10 hours in a day writing software, I cannot use a TKL or anything like that. I need it all. I wish I were a whiz and could figure out how to put mechanical keys in it, but I cant. I have many mechanical keyboards for fun, and I use them. But for really banging on my keyboard, I need my natural. Not the BS 4000, not the f'ed up Elite. The real deal Pro. I bought 4 of them about 10 years ago, just in case mine decided to kick the bucket, but haven't needed any of the backups yet, its still going strong.
That said. My first and favorite keyboard was my IBM PC model F.
If I could have that keyboard with the layout of the Natural Pro, I would be in heaven (and would pay good money, hint hint hackers).