I only have that Model M right now, I have heard the model Fs have a nicer feel and are more durability. The layout is a bit of a deal breaker for me unfortunately though, I like my full size board with numberpad : ) I have an old IBM ThinkPad though, a 770E.
The F AT layout is pretty nice. The only weird parts are the swapping of ctrl and caps lock, and the integration of the arrow keys with the number pad. I got used to it pretty fast, and many people ANSI mod their F AT or F122, which is fairly simple to do.
Then there's always a brand new F77 as well, although you won't have a full number pad and dedicated arrow keys at once, it would have to be one or the other, or an external number pad.
Nice. IBM struck gold with that aesthetic, and backed it up with quality.