My 0.1 cent answer.
I have an original FX-888D. GREAT! I soldered all that I did need with it, never it failed me, but I need to solder under microscope now and I'm looking for something else. Can I live without upgrade? Yes!
I can solder well under microscope but prefer something more ergonomics. It's impossible do it with 888? NO, I did it for months, but I need to solder soon thousands of really tiny SMD (0201 imperial and some 0402 metric!) components and I looking for something else.
The FX-888D have a crap interface... YES without doubt, BUT, when I solder I NEVER see the station and only change the work temp in extreme situations. This is not a toy to touch and see in HD, it's a tool, a reliable one to solder. Without detracting anyone, I think that much of the people that criticise the interface are programmers or hobbyst that prefer a rainbow in the screen to a proper set tool. Sorry. Hammers don't have UI and works. I set the temperature and not change anything else never more until I need to solder a really big component to a really extense pad. In this case I solder all with normal size and later solder the big components. That's it.
For $100 in USA for an original and tested unit that it's really ESD safe and did works for the industry for years, I think that it's a really convenient acquisition.
Forget the clone one's ! MAY BE are ESD safe, MAY BE works ok, MAY BE last for years as big brands last. Put money in something original.
Exist a "new" technology that uses an improve thermal transference and control. New JBC , Pace and Hakko stations use it. JBC and Pace has more power, Hakko it's ubiquitous and plenty of accessories.
I never did need more power than in my 888, but more it's preferable sometimes. I don't know if Pace and JBC has tweezers for his new solder stations, Hakko did (even have it for the 888). I like the micro iron optional to FX-951, but the Pace and JBC are close to it. But all of them cost almost the double that 888.
I'm 47 year old now, all of my best works and designs was soldered with the Fx-888D's grandfather and never the iron was a limitant. In my case, when I did get old I did get fussy and touchy and apparently "need" something better to solder under the microscope
. If I would have had to do it ten or fifteen years ago I would have been grateful (and amazed) to do it with my (now) old FX-888D.
But the new technology is better than the previous one, I'm not sure I need it, but there are times when it's good to treat yourself.
In other post I did ask for electrical information of these stations. My """clever intention"""" was do a cheap controller for an original handle with original tip and use it until the economics get better in my country and I can buy a original one base.
I never did think that something that I can build in one (or ten) days will be better that something thinked by experts and developed in the big brands and tested in industry for years. They are making perfect units for decades.
If I need to choose between an original 888 and a T12 clone I choose original. But for a month or two I can use a hybrid solution.
Shock convince me (with a lot of careful thinkinks and facts) for the PACE ADS201 but finally I did doubt because this model it's not selled in my country and obligates me to buy all the tips and accesories in USA with a big extra cost. Sends an envelope with a tip to my country from USA it's about half the cost of the complete unit in USA!
At this precise moment Greywoolfe offer a used FX-951 unit and then I did take the Hakko way again.
I can buy original tips, use it with the used original FX 951 and make (and use) for a while a DIY handle. When the economics get better I will buy a complete unit (if I need, I still have the 888!) complete the used station with an original handle an use it as second iron with different tip, handle or temperature set.
Even, if I need a tip for a specific work I can buy a clone tip and use it for few days without much hassle. Hakko it's the most cloned brand in the world it's plenty of clones in every chinese page and store in the world. There must be some reason for everyone to copy Hakko and not the others.
To resume:
I think that If you have the money and need it, buy the better that can you pay and sounds better to you.
But, if the money it's not a surplus, buy an original FX-888D or an used PACE/JBC or Hakko with new technology. In any case you can't fail.
All of this brands are good, all are great for the job. For some user some base has strengths that others not but depends heavily in the work to do.
You are the only person that knows if you really need to spend more money than the need to buy one fx-888D or similar from a big brand.