Apart from price, do you see any other advantages in Fuji Sensia or Kodak Elitechrome?
Absolutely. It's the only Fuji film that delivers nice, normal contrast and colors suitable for most scenes without any "special effect" look. I especially don't like the "digital" look provided by some chrome films, which comes mostly from blown-up highlights.
Velvia 50 gives exaggerated colors, especially skin tones. I like it, but it's not all-arounder by any means.
Velvia 100 and Velvia 100F are useless in most situations unless you shoot grey wall and want contrast and colors in it.
Provia 100F gives you blown-out highlights very easily. Very interesting and nice look in most situations but not all.
Provia 400X gives over-saturated, magentaish results. OK for some compositions.
Astia 100F is/was the only Fuji Professional film that is meant for photographing people, or mentioned as a low-to-normal contrast film.
Sensia was the "consumer" version of the previous version of Astia, IIRC. It has the same qualities. It's also the only film I can say that almost every shot was good. With 35mm, and when travelling, I usually have no time or interest to have several camera bodies with different films for different scenes. Or, when I have, the first one is for neg and another one for chromes. And, then I have to use an all-around chrome film, like Sensia 100. Velvia 50 would be my second choice. I find that all the other Fujichromes blow up highlights too easily.
But, now I finally have a reason to try Kodak slide films!