It's going to depend on your lab and your own equipment. Fuji E-6 films are actually supposed to get a longer first development than Kodak E-6 films, and not all labs distinguish. I find I get a legitimate EI 100 from Provia 100F, and if anything I'll sometimes underexpose it 1/3-1/2 stop to get more saturation.

In 35mm I prefer Kodachrome 64, though, for a medium speed transparency film, and I use Provia 100F pushed one stop when I need a little more speed.