This question cannot be answered in general, but for each person individually, only.
There are at least two short possible answers to this question in general:
1. (sounds a bit silly, precociously, but it's the shortest answer possible)
You need to find out yourself.
2. The question may be answered in reverse: (referring to "who do you think it's the right candidate for FreeBSD?")
Q: To whom is FreeBSD NO alternative? (The original Q of this topic)
A: For anybody who demands an operating system with the least personal effort at all
willing to pay the price by simply accepting and live unquestioning with what you're given.
Anything else needs more elaboration, from very personal points of view, which in any case only can be some kind of a guide that may give hints to everybody's own personal quest to find out themselves anyway.
A more comprehend answer you may get from e.g. :
HB, Chapter 1. Introduction
Explaining BSD
(I thought there was some article "To whom is FreeBSD, and to whom not" - but I cannot find it anymore; maybe was some introduction of a book?[help?])
Example:
someone who does online banking, checking emails and cares about stability
Those are all no issues to none of today's OS, even Windows by now is pretty stable
(Wanna hear old warstories from W95?
[We did not called it 'bluescreen of death'; too long, happened too often; it's just a 'bluescreen'
])
So decision's criteria need to be searched elsewhere; such as e.g. security, where IMO BSDs, then Linux were first choice.
It all depends on
your (personal) needs, knowledge, expectations, demands, will to learn...
What is your task? What do you want to do with a computer?
Which software do you need? Certain apps depending on some certain OS? Or are you willing to try, explore, and learn openly, not only other software packages, but further more alternative working processes - other ways to do things?
To summarize it inconsideratly, unfair but most primitively simplified:
If most you want is to play games, consume media, or browse the internet with the least effort possible, use Windows.
If games are your third priority, or less, you can live with it takes some effort to get some run, many will not run satisfiably or at all, or - even better - you don't care about games at all, but you actually want to become really good at computers, I recommend FreeBSD.
With Windows you don't really learn much about computers. You learn Windows.
To actually learn about real computering you need to enter the world of computer science, which means unix[like], for which BSDs are (a bit) more genuine than Linux.
If you want to learn or do programming: unix[like]
Every unix[like] is a software development environment by its very nature. Maybe not a very good one at high end stage at vanilla installation, but they always come at least with a texteditor, a C compiler, and a programmable shell, plus lots of choices you may add ([almost] all [major/important] programming languages are available on [almost] all BSDs and Linuxes. [Don't start no beancounting on that here, please!])
Also a bit of programming is always part of any unix[like]; I don't talk software development, but small scripts to automate processes, deal with config files etc.
If you want to learn/do networking, servers, firewalls... unix[like]
For a start on unix[like] I recommend FreeBSD.
If you want to become some kind of hacker one day - whatever this means to you - you will get to other BSDs, and of course Linux, anway. But for the start I recommend FreeBSD. RELEASE, that's 14.2 at the moment; not 'CURRENT', not 'STABLE', not '15'... -
RELEASE, installing all software by packages, only, not ports (except the kmod for the GPU to get a GUI). At least for the start, until you're quite well versed, know what you are doing, and why.
First be well-versed in moving self-confident within a house before start construction sites.
I hope I understood your question right, and gave you some useful answer.
