Throughout my life, I’ve kept myself busy a lot learning languages. In theory, I love all languages and linguistic subdisciplines. However, I do have a natural focus due to the country I am from (Holland) and personal favourites:
Germanic languages
Being a Fluent Dutchman, I am trying to learn as many Germanic languages as possible, from native to understanding it at a basic level: Dutch, English, German, Swedish, Norwegian, Danish, Afrikaans, Luxembourgish, Frisian and Yiddish. Other (regional) languages in this group might be partially intelligible for me, especially in writing. But the further away, (Icelandic) or small in number of speakers (Faroer) they are less interesting than larger languages or spoken closer to home. Some dialects within the Netherlands however, I understand and would like to learn some time.
Romance languages
I’m a huge fan of this often Mediterranean family. As a kid I learned some Spanish, also due to family. Since French and Latin lessons on high-school I became more interested in the three aforementioned and later Catalan, Italian and Portuguese. Being closely related, often as close as Chinese dialects, it’s relatively easy to learn a new one and I can speak above in order of appearance, again from fluent (Spanish) to basic (Portuguese) and all of the others (Romanian, Sardic, Corsican, Occitan, Galician, etc.) in writing but to a much lesser extend listening to them.
Slavic languages
Those years, I’m focusing on Russian and Polish. I want to master them first before learning other Eastern-Slavic languages such as Belarussian, and Ukrainain, other Western-Slavic such as Czech and Slovak and Southern-Slavic languages Bosnian-Croatian-Macedonian-Serbian (BCMS or BCS and Macedonian), Bulgarian and other (regional) languagesfrom its subfamilies.
Greek
I loved learning Ancient Greek in high-school, so I always have a warm heart and some understanding of its syntax, alphabet, lexicon of its modern equivalent. The phonetics (did you notice all those Greek words in linguistics and science as a whole)? are somewhat confusing though, such as η.
Indonesian
A friend at high school acquainted me with basic words and sentences in Bahasa Indonesia. It’s so awesome, easy considering its alphabet, grammar, pronunciation and a huge (and beautiful) country that it’s just a waste not to learn it! And similar Bahasa Malaya can be an interesting follow-up after reaching some fluency to see the similarities and differences later!
Semitic languages (Arabic, Hebrew, …)
I’m learning Modern Standard Arabic (MSA), before digging into national/regional dialects, so I can have a better understanding of all news and media from the Middle East and up to some extend, from Northern Africa.
In the meantime I’m getting myself acquainted with Ivrit, and the Hebrew alphabet. But I don’t want to mix them up, so I’ll focus on Arabic for now.
Turkish
Another interesting language I’m learning cause of its difficulty to me, is Turkish. Although most words are not related to any language I know, I like the loanwords from French and Arabic. The completely unique syntax of suffixes is a great challenge, but it helps that all are in Roman letters.
Chinese
As the only language from the Far East for now, I’m learning Mandarin Chinese and its simplified character system from China. Once it’s fluent, I’ll have a closer look at the traditional character set now used in Taiwan and other languages such as Cantonese.
Esperanto
Just for fun and to speak a constructed international auxiliary language, I decided to learn it a bit at a polyglot conference to speak with other attendees. It’s easy, although it felt unnatural at the beginning, because I was confusing word endings with false friend conjugations or pluralizations from Romance languages. After a while, it’s a lot of fun!
Other languages that I want to learn later
The above dozens of languages are enough for me. I prefer learning a new one from each subfamily once I am comfortable with the previous ones. I don’t want to confuse myself. Other interesting languages for later are: Swahili, Japanese, Korean, Berber, Papiamento and many more!