I can't speak to the availability issue, but my standard choices for serious color work are Portra 160 in 35mm and Ektar in 120. Not sure why, but where the palette of the Portra works for me in the smaller format, it seems too subdued in 120. Ektar is definitely more saturated, and it is also less forgiving of exposure errors, whereas Portra has incredible tolerance, especially for overexposure.
I also shoot a fair bit of consumer-grade stuff, mostly Kodak Gold 200, with some Gold 400 and Fuji Superia 200 on occasion, when I'm just messing around. None of it is really bad, though I prefer Kodak's colors, but none of them have the same quality as the professional-grade films.