For looks, the Corona 4 would be my favorite, though I never type on mine because it has a fragile feel to it, especially the carriage.  For actually using as a portable outside of the house, I prefer the Remington 2, because the geared typebar action—which I normally don’t care for—is really good for typing in positions that are unideal, such as on a coffee table in a hotel room, or in one’s lap. Overall, my choice would be the Royal P. My Crinoline Blue Royal P is one of my prettiest typewriters, for a 20’s machine it has a nice action and carriage return feel, and Royal is the brand I am most familiar with servicing and repairing. My second favorite overall would be the Underwood 4-bank, because it also looks great and has a decent action.  My favorite era for typewriters is the mid-late 1930’s, though, and I do most of my typing on standards.