People ask me for camera recommendations all of the time. I try not to give universal answers because I don't believe in any sort of one-size-fits-all. When it comes down to it only your own experience, desires, psychology, and well understood needs can dictate what camera or better yet camera system is the right one for you.
Cameras Come & Go, Lenses…
Just for a moment let's consider all things equal. All of the other stuff neutralized when it comes to camera selection and system choice. If this were the case I would have to say that Fuji is the system entirely because of the lens line-up. If you've been around the block more than once you have to know bodies come and go but lenses seem to live on forever. Hell, I have some Nikkor lenses I bought 30 years ago I'm looking at right now. It's funny how most people make system selections based on cameras when they should be looking at lenses.
Yes, yes, I know, now that you're stuck with one sensor permanently welded into a camera body that counts a lot. Yep, but let's backtrack a bit. Who doesn't know by now that whatever that sensor might be comparatively at the moment it means nothing or next to nothing a year or two from now? Hell for that matter so do most performance metrics. Sure if a particular system just will not cut it for what you need today that's a consideration. Beyond that buying for theoretical need based on nits is kind of insane.
With that in mind, almost any way you slice it Fuji's glass for the X-System is fantastic. Let's count the ways.
Honestly I don't think there is a better value in lenses out there. You get a lot of bang for the buck with Fujinon glass. Is there any lens that crosses the $1,000 mark? I would have to check but by and large all of them are under that one thousand dollar mark in the USA. Most of them by a large margin at real-world prices with frequent discounting.
I'm sure some of the super-tele stuff coming down the road won't be but compare that to Nikon, Canon, just about anyone out there. Sure, they have a few sub-1k lenses but almost every one that serious photographers actually wants is way above that magic mark.
Quality & Feel
In terms of optical performance they are as good or better than the average. In many cases they are on par with some of the best glass I've ever used. Every single one seems to deliver in the quality department in most ways. Sure if you go out there and look really hard you can find some examples that Fuji probably cannot match. Let's say the Zeiss Otus lenses for instance. Really? Give me a break, I wouldn't buy one of those if money were no object at all. Have you seen the size of a 50mm prime? Not a chance. In a lot of ways that's like comparing a camera lens to the Hubble or something; Nice trick but let's get back to stuff most of us are actually willing to use.
In my book build and feel count a lot. I like my stuff to feel nice and look nice. Hell I spend so much time with it that's got to count for something. I'm not at all saying that Fuji lenses feel the best of anything available. Most manual focus glass feels better in the hand. Compared to just about every other auto-focus line-up out there I would have to put Fuji's feel and quality pretty high on the list if not absolutely top notch. This is across the board, not just here or there.
I could be eating my words five years from now. Only time will tell about absolute quality in terms of longevity. How a lens feels is one thing. How long it lasts and performs is quite another. I don't think any of the X-series lenses has been around long enough to see how they hold up for all the things you can't see and touch. You know important stuff like focus motors, sensors, switches, and the rest of the electronic gobbldy-gook that makes them work at all. If any of that stuff is not durable the lens won't work at all. It's all fly-by-wire.
Look, The Most Important Part
What's uncanny about the X-System lens line up is that every single one of the looks really good. Isn't that important? I would much rather have a lens that renders something I think looks great than one that I dislike but resolves more detail in some lab. Forget the lab, even if that's the case on a tripod shooting something flat.
I don't shoot flat things at infinitely small apertures or idiotically high shutter speeds on tripods. I make pictures of 3-D objects at large-ish apertures relatively close to the subject. Hell even on the rare occasion I am at f/8 there's only a tiny but of my photographs that are technically in focus. By and large most of the frame in most of my photographs are out of focus to one degree or another. I care far more about how all of that looks than if the in-focus part can resolve 100 lpm or 102 lpm.
Every single lens I've used so far has been shockingly good in terms of how it looks everywhere. Even the wide lenses which are usually varying degrees of awful to less-awful are gorgeous. I've never experience this overall great look across the board with any system I've ever used. Not Nikon, not Leica, not Hasselblad/Zeiss, none. What's more is they look great at just about any focus distance, at any aperture.
Just one tiny example; That last image. All the rest are from my reject pile. That last one I love. Of course which lens I used wouldn't influence if I loved it or not but it does serve a tiny bit as what I mean by look. Shot at f/8 at the 18mm end of the 18-55mm. Take a look at the obviously out of focus areas at the left of the frame.
I would put his in the category of looks pretty damn good. Now take in to account that this is a friggin' zoom with a gillion elements at f/8. Most wides just look like rat crap in the out of focus areas, even the Leicas. I know the wide end of most Nikkor zooms do. Hell a lot of Nikkor wides are on the ummm, meh side of things and most are on the awful end of the spectrum like the 18mm AiS.
All things being equal nobody else, not one other company has a suitable APS-C glass line-up across the board. Broadening that a bit to include all the formats buy into the X-System for the glass. I was impressed from Day One with the first three and surprisingly it's only gotten better and better. There really isn't even one turd yet. Amazing.