Simple...shoot whichever one you think looks best! Why would you ask someone else how your image should look?
Many people prefer neutral. I personally prefer Landscape. If I don't plan on grading, I turn down the contrast 1 notch and the saturation up 1 notch. Of course, these settings change about 20 times a day depending on changes in light, angle, lens, subject, etc. I never shoot a single setting all the time because that just doesn't make any sense. On a cloudy day in the city, I turn up contrast and saturation to +2 and adjust the white balance so that everything is extremely blue. Completely unconventional and unrealistic, but that's the beauty of it! If I want it to look a little more film-like, I'll shoot with low contrast (not "flat") and overlay a film grain in post.
The best thing you can do is experiment. Start by shooting the same shot with each picture profile with matched settings and determine which you like best. Then experiment with the individual levels to get the desired contrast and saturation, although I can't stress how important it is to turn sharpness all the way down on a DSLR.
Getting your colors in-camera can be a challenge, but in the end it will look better than shooting flat and grading if you become proficient enough. I know there's many (strong) opinions about this, but the thing is, it's a mathematical fact. DSLR footage isn't meant for heavy grading, and when you rely on it, you damage the image. And the only bonus is having more freedom in post, which isn't even a perk if you're patient enough to get your colors in-camera!