Nothing against Alpina or Olympia SM-series owners, because I am sure these are first-class typewriters, but I still stand behind my 1952 Royal HH standard typewriter.  It is a robust, almost indestructible machine with a still pretty good availability of spare parts.  I also own two Olympia SG machines, which one day I will fix.  But, if I were to pick just one, it would have to be the stalwart Royal HH.  

I'd have to say the SG1, with the SG3 as an alternate.

If you're looking for a looker and an overall great machine, I'd do a Royal 10. They have that classic look with high gloss paint, and two (or four) side windows on the machine for looking inside.

I personally really like the touch, but you can also adjust the touch with a touch control, which many other machines at the time did not have easy access to. Even the early Royals have the great "snappy" action that many other collectors talk about. They're solid and sturdy, but lack the refinement and the features of later typewriters, such as a key-set tabulator and automatic margin sets.

Actually... now that I think about it, I might just choose the Royal 10 as my #1 pick!

The key to the question is the criteria that you can only have one standard. So, are you a serious typist? Or someone who just punches a few keys on occasion? If you're a poser, then any standard you like the look of will do; they all type well enough to satisfy someone who only dabbles in typing. However, if you need a real workhorse, one machine that does it all, is feature laden and performs exceptionally well, then you have to be far more discriminating.

I own all of the models that have been mentioned so far in this thread, and I would choose the Olympia SG1. It's the complete package, period. I can't think of another standard that can match it for features (paper injector, quick carriage release, double character spacing, a FIVE position vibrator, paper rest, touch control, a jammed key release, spring-loaded keys, etc.). Of all the standards that I own it's my go-to machine for getting work done. And there's a reason that there's an SG Owners' Club here, and why it's so popular.
 

colrehogan wrote:

...what would one need with a five position vibrator?

Oops, sorry, I messed up... I should have written a FOUR position vibrator instead: 
1. Stencil mode - Highly unlikely it would ever be needed, but for those who have a mimeograph the option is there.
2. Black - Use the top portion of the ribbon.
3. Red - Use the bottom portion of the ribbon.
4. Yellow - Use the middle portion of the ribbon to get every last bit of ink out of it.

Olympia's instructions for the penny-pinching black ribbon buyers out there: Use up the ribbon in the black position first, then switch the vibrator to the yellow position. When the ribbon is used up in the yellow position, flip the spools over and switch the vibrator back to the black position.