Klingon
Lojban is a language based on the principles of logic, which has a goal to have a completely regular and unambiguous syntax. It also gives people a great amount of freedom in how they express themselves, for instance by not forcing them to specify such things as number, gender or tense (for instance, the sentence "mi viska do" can mean "I see you(singular) right now", "We will see you(singular) in the future", "I have seen you(plural) in the past", "It is always true that we can see you(plural)", and so forth).
Another goal of Lojban is cultural neutrality (for instance, while Esperanto's vocabulary is based primarily on European languages (making it much easier for the average European to learn than the average Chinese person), Lojban's vocabulary is based on the six most widely used languages in the world, so that people from completely different background can have an equally difficult time learning the language), and it's designed to be easy to pronounce (whether or not that goal has been met is a matter of some debate).
Klingon's goals are slightly less lofty. While Lojban has its roots in a language that was created for scientific study (Loglan), Klingon was originally constructed for the purpose of translating a few lines from some of the earlier Star Trek films. Now, while Lojban is designed to be easy to pronounce, Klingon is designed to sound alien, and as such many people find it very DIFFICULT to pronounce. Klingon also does not share Lojban's goal of being syntactically unambiguous, or to provide speakers with the same amount of freedom that Lojban does; Klingon is meant to come off as a natural language, not a perfect one.
Now, if the question is "Which is best?" or "Which do you prefer?", I can't really give you an answer.
Lojban is incredibly well-designed, having been painstakingly crafted over decades to meet certain criteria. However, it is alo very difficult to use in conversation; it can be difficult just constructing a correct sentence, and once you've done that there's still a large risk it doesn't say what you want it to say.
Klingon is a lot more crude, but it's still a lot of fun to use, and while it's difficult to hold long, philosophical debates in the language, I'd argue that it's considerably easier to discuss everyday matters in Klingon than in Lojban; while it's very different from Earth languages in its composition, it's still similar enough to feel natural once you get used to it.
In the end, I have found that both are a lot of fun to study, in part due to the various challenges that they pose; their alien nature - by accident or design - force one to rethink one's way of expressing oneself. Just take a simple thing like the fact that Klingon deos not have a word for "Hello!" (forcing you to rethink the way you start conversations), or the fact that Lojban allows you to play with so many different linguistic nuances (or to abstain from using the ones present in your own native language)... It makes every conversation an intriguing puzzle!
They also both have intriguing communities that are dedicated to exploring these languages, or to just play around with them. With Lojbanists, you can have a long discussion about what an opera house really is in Lojbanic terms (perhaps zgidracydi'u (music:ish-drama:ish-building(s))?), or whether space and time should be spoken of in Newtonian terms or in causal ones à la relativity theory. Among Klingonists, many discussions center around how one's "human bias" colors one's expressions, with questions such as "Can a day be happy?" and "When does the present tense need to be explicitly stated?".
bau lo lojbo
.i lo bangrtlingana no'u la klingon. je no'u la bantuluxe cu runti bangu .i se finti la'ogy.Marc Okrand.gy. noi bauskepre ku'o mu'i tu'a lo ranmi pe la .star.trek. .i lo datni cu zvati zoi gy.www.kli.org.gy.
ni'o la .nitcion. .e la .mark. cu ge lojbo gi se bantuluxe
Source
If you want to know more about constructed languages and the people who speak them, I can really recommend the book "In the Land of Invented Languages" by Arika Okrent. It discusses both Klingon and Lojban at some length, as well as many other interesting languages and fascinating people.
Discussion
If it may be argued that different conlangs are in competition for the same audience of potential learners (which is not in itself a given), then Klingon poses a much more visible threat to Lojban than do other conlangs, including Esperanto. Klingon has glamour and visual media on its side (which Lojban does not, and will not), as well as being a conlang rather unlike English (which is also a selling point of Lojban), but not extremely difficult to master (which is not a selling point of Lojban).
Its culture is small but vibrant, and translations of "Hamlet" and "Gilgamesh" have already appeared in book form. Prominent Lojbanists Nick Nicholas and Mark Shoulson were involved in the former.
Though Lojbanic culture need not follow the fannish model of language development, it should find food for thought in such lavishly detailed tomes as "The Klingon Way" (a collection of fictional proverbs) and "Klingon for the Galactic Traveller" (a disquisition into much fictional Klingon culture and associated idioms)...
The two languages are complementary in a different way (than Lojban and Esperanto) - Lojban is thought to be serious and scientific, Klingon frivolous and fantastical. But this disregards the amount of hard work that was necessary to give Klingon the usability it now possesses (for it was never intended as a real conlang, in the beginning), and also the unacknowledged amount of fantasy and frivolity in Lojban culture.
Lojban and Klingon are completely different in their design philosophies. The point of Klingon is to zealously stick to the canon created by Mark Okrand. The point of Lojban is to create a complete, interesting, logical language, whose design principles are not arbitrary. Does this underlie la .nitcion.'s extreme hardlinerism?
- nitcion:
- Easier to explain through Esperanto's "Netusxebla Fundamento", actually. Especially considering that hardlinerism isn't the same as fundamentalism, which is what the sort of thing you're postulating would engender. The forward to Esperanto's "Fundamento" says: "The Fundamento must stay strictly untouchable, even along with its errors." ("La fundamento devas resti severe netusxebla ecx kune kun siaj eraroj"). This may be very sensible for Esperanto, but it's just plain silly for Lojban.
- Ahem. Do the Klingons mention Lojban on their Wiki?
- Inasmuch as they don't have a Wiki, the question is meaningless. Lojban is certainly mentioned on their mailinglist, by persons other than me and Mark, and not with universal derision. And you may be delighted to see kli.org/kli/langs/KLIlojban.html.
- nitcion:
- .i mi ji'a morji lo se du'u zo'e .e'a cusku loi lojbo steci pe bau lo glico .e ro da pe bau la .lojban. kei ne lo mriste lidne bo notci .i gonai lenu skicu lo bantuluxe bau la lojban. na se curmi da (to ca'i ma? toi) ki'u lo ka na steci la .lojban.; gi lenu skicu loi sralo pu'e sevzi pajni .e la .maikl.everson. .e lei namcu pe la gedel cu ji'a na se curmi da
- .kreig.daniyl. disagrees with the transliteration of tlhIngan. Read transliterating 'tlhIngan' page.