I just found out about this:
http://www.esperanto.org.uk/education/exams.html

What is the most recognized/useful certification for Esperanto?

Do you personally have a certification?

There are a number of exams that you can take, given by various organizations, that will give a certificate to say you passed the such and such level exam.

Some people like to take these exams just to have a piece of paper that says they have reached a certain level. There are few situations where you would actually need such a piece of paper. I cannot think of any situations but I know there is a degree program in interlinguistics that is conducted in Esperanto through a Polish university. You need to speak good Esperanto to participate but I think a brief interview is sufficient to show your knowledge and I don't think they ask for an exam certificate.

It may be that some universities would allow you to show such a certificate to meet their language requirement but I have no idea which universities that might be, I suspect it would be on a case by case basis. Maybe in Hungary that would be accepted but I think Hungary has its own system of language exams that you need to pass, not the usual international ones that the rest of the Esperanto world uses.

I don't personally have a certificate of any kind.

Alkanadi:What is the most recognized/useful certification for Esperanto?
Do you personally have a certification?

Useful for what purpose? I don't remember the subject ever coming up in a conversation with Esperantists, or being a requirement for any Esperanto event (though one needs to pass the 'C' level exam on this website to be eligible to become a tutor for beginners).

However an examination can be a useful challenge and stimulus to work at the language.

I have gotten certificates for Esperanto courses and examinations, but I'm not aware that they helped me professionally in any way.

Alkanadi:What is the most recognized/useful certification for Esperanto?

The Common European Framework of Reference for Languages is certainly the most prestigious of the language exam systems where proficiency in Esperanto can be tested. Read about it in Wikipedia (in English or Esperanto) or in edukado.net (Komuna eŭropa referenckadro por lingvoj, KER).

The system was initiated by the Council of Europe and it is widely recognized in Europe and in some other countries.

You have only to look at the criteria for the various levels of competence to see how much the common framework has been developed to be appropriate to national languages ie those used in everyday living in a certain society.

Competence in Esperanto seems to me to more appropriately measured by a different set of criteria, to do with the level of understanding of how the language works.

However, that you can take exams in Esperanto that purport to be at a certain level comparable with an exam in some foreign national language, is no bad thing from a propaganda point of view.

Competence in Esperanto seems to me to more appropriately measured by a different set of criteria, to do with the level of understanding of how the language works.

Well, "understanding how the language works" doesn't seem to always correlate with "proficient speaker". I know a lot about how Greek works, but on no account am I a proficient speaker.

Being fluent in Esperanto means about the same thing as being fluent in other languages, e.g. Can you say what you want to say spontaneously and naturally, in conformance with the accepted rules of the language? Seems to me like social application is mostly a by-product of fluency. You can be B2 or C1 in Esperanto (or any other language) in terms of proficiency without actually using the language at that level (as long as you could in principle).

I have a C1 KER diploma and I'm glad I did the exam, because with regard to its aspect the diploma is the nicest I've ever gotton, much more beautiful than my master and PhD diplomas.

The reality is that most Esperantists are some way off the degree of fluency that they would have in their mother tongue, simply because they don't have the opportunity to speak the language that often.

At the same time they may have a very sure touch concerning what constitutes good Esperanto, comparable to the degree of mastery that an educated speaker may have of his mother tongue.

The odd thing about Esperanto is that many spertuloj will have an almost native speaker like authority about what is well formed in the language (or what is an appropriate word) without the automaticity that flows from using a language on a daily basis for everyday living.

Because of this peculiarity, it seems to me that the appropriate criteria for competence in Esperanto are somewhat different to those you might apply with a national language or those of the common European reference.

Certainly if we were just to judge competence in Esperanto by fluency or by applying some of the criteria of the KER we would be missing the point.

In particular, an Esperantist may have command of the language at C1 level (Can produce clear, well-structured, detailed text on complex subjects, showing controlled use of organizational patterns, connectors and cohesive devices.), yet in conversation might be judged only at A or B levels because of his lack of fluency.

Putting it another way, the KER levels may be reasonably judged as progressive in respect of competence in a foreign national language - competence at a C level is arrived at after competence at a B level, which is turn achieved after A level competence.

Yet an Esperantist may be rightly judged to have a C level type competence in respect of knowledge of the language, whilst only performing at a much lower level in any time-critical situation, and in respect of activities like interacting with native speakers, or being able to order by name certain goods in a shop, or using the language in many other everyday situations which are not part of the Esperantist experience.

The Esperantist who has dealt with his tax inspector in Esperanto, or had his car repaired in an Esperanto-speaking garage, or had to remonstrate with an Esperanto-speaking plumber/electrician/builder over some maintenance issue would be a very rare fellow.

Putting it another way, the KER levels may be reasonably judged as progressive in respect of competence in a foreign national language - competence at a C level is arrived at after competence at a B level, which is turn achieved after A level competence.

Yet an Esperantist may be rightly judged to have a C level type competence in respect of knowledge of the language, whilst only performing at a much lower level in any time-critical situation, and in respect of activities like interacting with native speakers, or being able to order by name certain goods in a shop, or using the language in many other everyday situations which are not part of the Esperantist experience.

Couldn't you say this about other languages?

My grasp of Greek is quite advanced if you were to consider purely my theoretical knowledge (this is how declension X inflects, this is how consonants are modified in compound words) but I am hopeless in a spontaneous conversation due to the time it takes to process the knowledge. And I can't go to Bob's Auto Repair and speak Greek any more than I can speak Esperanto.

Presumably in Esperanto theoretical knowledge can more easily overtake practical speaking ability, but it doesn't seem farfetched to say the same of other languages (it's just harder because you normally need the speaking ability first, in order to advance/solidify your theoretical knowledge).

Tempodivalse:My grasp of Greek is quite advanced if you were to consider purely my theoretical knowledge... but I am hopeless in a spontaneous conversation due to the time it takes to process the knowledge

Have you tried reading out loud to yourself? Or, memorizing some simple text?

I think this will help your brain form "word clusters" and recognize patterns of speaking.

I do this with Esperanto and it seems to help a lot.