I know this is quite an old post, but having just acquired an Alpina SK24 and already being the proud owner of a Hermes 3000 and a mint Olympia SM4, I gotta agree.  The Alpina is special.  It deserves to stand with the other two.  I find it strange that more people don't list it on "Greatest Typewriters of All Time" lists.

A Silent super. 

My "4" would be:
1: Erika model M (in production until 49!)
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2: Erika 10
3: Olivetti lettera 32 
4: Olympia SM4 (over the SM9 mostly because of styling).
Never used a Hermes 3000, people demand too much money for them these days. 

But of cause all of them pale im comparison to even a basic office machine. Except the M. Best touch out of any machine I ever used, even including my refurbished 1961 SG1 with new rubber. Not even close.