I love shooting slides on my Leica M6. They look great. I've always loved chromes! I mostly scan for output and I really loving being able to put the slide on a light table and match the color to the monitor, and I even love to project them here and there.. I don't really care for the dumb c-41 orange negatives that I can't really read well.
My all time favorite is Astia 100F, such natural beautiful colors. Of course no more of that in 35mm, so I heard Kodak E100G was a good replacement, but alas it's gone too.
Velvia is just too saturated typically for what I like, I may have to give Provia another chance
SO now what do I shoot?
Maybe I'll break out the Rolleiflex and slap some 120 astia in it.
I'm very much like you. I love slides. In all formats. The bigger the better. Fuji Provia is probably your best option since it is currently available. I have never had the pleasure of Astia largely because I am a landscape photographer who mostly used Velvia 50. But now that I am getting older I am starting to appreciate the subtleties of Provia over Velvia 50. Now would be the time for me to try Astia but, alas, it is no longer, and I don't want to start liking it knowing full well that it's discontinued. So for the time being Provia is my film of choice. It is quite beautiful, especially in 120 and 4x5. Velvia 50 is good too, but you have to know when to use it. It's not for everything, like I once thought.