No.  There never are.  All criteria are fuzzy and useless.

  Which is the best car?  How do you choose?  Here's how this works: You
  look at a few cars, far from all, then feel good about a few models.
  Then you construct an elaborate rationalization for why these are the
  good choices and all other cars are useless pieces of metal and plastic,
  gas-guzzling deamon machines, etc.  Then you tell your friend(s) and
  colleague(s) and spouse(s) and kid(s) and cat(s) why these are the good
  choices, mainly to convince yourself.  Then perhaps you look at one or
  two or three completely irrelevant attributes of the models you think are
  good, and wind up with a single choice -- this is the car you want!  Then
  you make up an even more elaborate rationalization for your choice and
  you memorize a lot of technical details about your car, but know nothing
  about any other car (except possibly your last, if you still remember).
  That you only know your chosen car is quite irrelevant, since any friend
  or colleague or spouse or kid or cat who has done the same thing for
  another car will just tell you _their_ memorized technical details and
  you can play a very manly game of "compare random meaningless numbers" in
  which every single participant wins, knowing with ever more certainty
  that his chosen car was the best possible choice all along.  You might as
  well just make up reasonable numbers and lie.  Nobody will know or care.
  Then you are a happy car owner and you really enjoy the greatest car ever
  and you polish it and care for it and give it a pretty name that you do
  not disclose to your spouse.  However, if this should in _any_ way fail
  and the self-convincing magic breaks down in a fit of objectivity and
  rationality, you try very hard to glorify the miserable piece of metal
  and plastic so some hapless second-hand victim will be utterly convinced
  not only that _he_ is the lucky one who gets your used car, but that he
  should finance your next car, too, in fact that he is _much_ better off
  with your used car than the new car you want, considering how much you
  cared for it and nobody has cared for a new car, yet, have they?  No.

  So the criterion is this: That you are happy with your choice.

  The catch is that absolutely every car that has ever been sold _is_ the
  best car ever, but _was_ a piece of junk.  Every single owner of a car
  will argue exceptionally well for his current car, completely oblivious
  to any facts to the contrary, and will present strong qualitative and
  scientific evidence to support his case, yet without any trace of effort
  will change his mind when it has been sold, peaking in his evaluation
  just prior to closing the deal.  If it was the right choice to buy, it
  was certaily the right time to sell.  Mistakes do not happen when you buy
  or sell cars -- it is too damn essential to your life to make any sort of
  mistake with such an acquisition, so you just don't.  It is that simple.

  Of course, none of this is emotional.  Buying a car because you feel good
  about it is hopelessly immature and ridiculous.  Nobody does that.  Well,
  maybe your stupid neighbor who clearly cannot afford showing off like
  that, but at least nobody _normal_.  Being able to defend your choice
  rationally is probably even more important than actually buying the car.

| Are these groups of languages basically two different tools for two
| different jobs, or are they essentially competing for the same
| "ecological niches", such as for example machine learning, expert
| systems, compilers, etc.?

  No to both alternatives.  That you can drive your car to work is the
  single most irrelevant consideration that went into your choice.
--
  In a fight against something, the fight has value, victory has none.
  In a fight for something, the fight is a loss, victory merely relief.