Well, a lot -- most of this, actually -- depends upon what you prefer to shoot....and unfortunately sometimes that takes a while to figure out! What for me is a pair of favorite lenses (Sony's 90mm macro and 100-400mm zoom) might not be at all be appealing to or right for someone else. Of course I have other lenses, and they're great for various purposes and specific scenes, but they aren't my favorites. Neither of those two favorite lenses is especially fast, actually, as the 90mm macro is f/2.8 and the the 100-400mm zoom is variable depending upon the extent to which one zooms.
It takes time to develop a sense of which lenses will work for you in the way that you want and need -- and that is good, as it gives you time to really assess what you like to shoot, and what lens(es) support that along with what you want to have and use "just because." This stuff isn't inexpensive, though, as we all know! I'm retired, not wealthy and am on my own, not financially supported by anyone else, so it takes me a little longer than it might others to get the lenses which I think will work out well for me in specific shooting situations.
One thing I learned a long time ago, though, back in my Nikon days, is that more often than not, faster is usually a better choice when it comes to lenses. Unfortunately, usually faster lenses are more expensive. Another thing I also learned, too, is that in the long and the short run, going for genuine quality right from the start makes a difference and in the end makes more sense all the way around than buying cheap junk just to get some gimmicky pseudo-effect. As most people on here realize, too, in general I am not a fan of buying third-party lenses, so can't offer any recommendations with regard to either Sigma or Tampon lenses. The extraordinary Voigtlander lenses are the exception, and I do have three of those (two of which are macro lenses. Gee, do you think maybe I really love macro??!).
Getting back to fast lenses: yes, I have a couple of lenses which are f/1.2. Most of the time I don't shoot with them wide-open but occasionally I do -- just for the heck of it and because, well, I can. One is the fantastic 50mm f/1.2 Sony GM and the other is the equally fantastic Voigtlander f/1.2 35mm. Most of my lenses are either f/1.4 or f/1.8mm, except for the long zooms, which have variable apertures.
When I first started out, somewhere along the line I bought the Sony f/1.8 35mm and the f/1.8 85mm lenses. After a while I realized that I would definitely appreciate and use the 35mm f/1.4 GM fairly frequently, so eventually purchased that lens. It's surprising, the difference between f/1.8 and f/1.4, as you wouldn't think there would be that much, but there actually is. That 35mm f/1.4 GM is a gem of a lens and if you do a lot of shooting in that general range, this is at some point the lens to have.
However, I haven't replaced my f/1.8 85mm lens as I really don't seem to use it all that much -- I don't shoot many portraits which is what that 85mm is especially good for, and doubt that I would use the f/1.4 version any more frequently. f/1.8 is plenty fast enough in the situations in which I do use it. The f/1.8 versions of the 35mm and the 85mm lenses are excellent in their own right and are surprisingly reasonably priced, which is a pleasant treat coming to us from Sony. They're good for starters, to see how often you would use their respective ranges and whether or not you feel you would benefit from f/1.4 as opposed to f/1.8.
So....my suggestion would be, if you're interested in portraits, go for that 85mm f/1.8, see how you like it, if it does what you'd like.... There are rumors that there is a new version of the 85mm f/1.4 GM on the horizon, and that would be worth waiting for, as some users report various issues with the current 85 f/1.4 GM. Sony may possibly even bring out an f/1.2 version of the 85mm, which I think would be a real thrill to a lot of portrait photographers. (Unfortunately the price tag will most likely NOT be so thrilling!)
Wide-angle lenses.....I don't do a lot of shooting where wide-angle is required, but I do have the lovely little 20mm and I also have the astonishing 12-24mm f/2.8 zoom wide-angle lens. Many Sony users go for the several other wide-angle lenses in-between, 16- something, that are on offer, which are very popular and well-regarded. I think there is a power zoom version (that may be APS-C rather than FF, though) along with other versions.
Sony offers us so many wonderful choices in lenses...and that is both exciting and at times overwhelming!
