Okay, rating languages by simplicity is *incredibly* complex and subjective. There's no single, universally accepted metric. "Simplicity" itself is multifaceted – does it mean simple grammar? Simple pronunciation? Small vocabulary? Regularity? I'll do my best, explaining my reasoning, and with a *lot* of caveats. I'll break it down into tiers, with explanations for *why* I'm putting languages where I am. **Keep in mind, this is a generalization, and many individual languages *within* families will vary.**

**Important Caveats Before We Start:**

* **Native Speaker Bias:** What seems simple to a native speaker will be different for a learner.

* **Aspects of Simplicity:** I'm focusing on a combination of factors: morphology (word structure), syntax (sentence structure), phonology (sound system), and regularity. Vocabulary size is less of a direct indicator of *simplicity* as it's more about how *much* is expressed.

* **No Perfectly Simple Language:** All languages have complexities.

* **Creoles & Pidgins:** I'm generally excluding (or giving special mention to) creoles and pidgins because their simplification often comes from a mix of source languages and a reduced feature set, making them somewhat different than naturally evolved languages.

**Here's my tiered ranking, from simplest to most complex (with explanations):**

**Tier 1: Extremely Simple (Languages with very streamlined grammars)**

1. **Toki Pona:** (Constructed Language) This is *specifically designed* to be simple. It has only about 120 words and a very basic grammar. It's an outlier because it’s *not* a natural language, but it exemplifies the extreme end of simplification. (Used mostly by hobbyists and for philosophical thought experiments)

2. **Mandarin Chinese:** While its writing system is incredibly complex, Mandarin's *grammar* is remarkably simple. It has no verb conjugations, no noun declensions, no grammatical gender, and a limited number of inflectional morphemes. Word order is relatively fixed, but this is the main driver of grammatical relationships. Tone is a complication for learners, but doesn’t change the core grammar.

3. **Vietnamese:** Like Mandarin, Vietnamese relies heavily on word order and lacks inflectional morphology. It has a complex tonal system, but its grammar is relatively straightforward. It's also largely analytic, meaning grammatical relationships are indicated by separate words rather than inflections.

**Tier 2: Simple to Moderately Simple (Relatively straightforward grammar & pronunciation)**

4. **Spanish:** Spanish has relatively regular verb conjugations and noun genders, but compared to many languages, it's fairly predictable. The pronunciation is mostly phonetic (what you see is what you get). Sentence structure is generally Subject-Verb-Object, although more flexibility exists.

5. **Swahili:** A Bantu language, Swahili has a relatively simple sound system and a consistent grammar. It uses prefixes and suffixes extensively, but these are generally consistent and predictable. Noun classes exist, but are less complex than in some other Bantu languages.

6. **Indonesian/Malay:** These are very closely related languages with extremely simple grammar. They have no verb conjugations, no noun declensions, and rely heavily on word order and particles to indicate grammatical relationships. Pronunciation is generally phonetic.

7. **Turkish:** Agglutinative language (adds suffixes to words to express grammatical function). While it *has* a lot of suffixes, they're relatively regular and consistent, making it predictable. Word order is fairly fixed.

8. **Esperanto:** (Constructed Language) Designed for international auxiliary language, Esperanto's grammar is regular, agglutinative, and relatively easy to learn. It aims for simplicity and clarity.

**Tier 3: Moderately Complex (Start to see more irregularities & complexities)**

9. **English:** This is a tricky one. English has lost much of its inflectional morphology (verb endings, noun cases), making it simpler in some ways than its Germanic relatives. However, it has a large vocabulary, many irregular verbs, and a somewhat flexible word order. The pronunciation can be very inconsistent.

10. **Russian:** Russian has a complex case system (six cases), verb conjugations, and gendered nouns. However, the grammar is relatively logical, and the rules are generally consistent. Pronunciation can be challenging for English speakers.

11. **German:** Similar to Russian, German has complex noun cases (four cases), verb conjugations, and gendered nouns. Word order can be quite flexible and dependent on context. The compounding of words can also make it challenging.

12. **Portuguese:** More complex than Spanish, with more irregular verb conjugations and nasal vowels. The pronunciation can be tricky, and there are subtle grammatical differences between dialects.

13. **Japanese:** Japanese has a relatively simple sound system, but its grammar is quite different from Indo-European languages. It has particles to mark grammatical functions, a complex system of politeness levels, and a subject-object-verb word order.

**Tier 4: Complex to Very Complex (Significant grammatical challenges and/or irregularities)**

14. **Arabic:** Arabic has a complex morphology, with verb roots and patterns that can be difficult to master. It also has a complex system of noun gender and number, and a relatively flexible word order.

15. **Hindi/Urdu:** These closely related languages have a complex verb system, noun genders, and postpositions (similar to prepositions, but placed after the noun). The case system can also be challenging.

16. **Hungarian:** Agglutinative language with a very complex case system (around 18 cases) and a large number of suffixes. Word order is relatively flexible.

17. **Greek (Modern):** While simpler than Ancient Greek, Modern Greek still has complex verb conjugations, noun declensions, and gendered nouns. Word order is relatively flexible.

18. **Basque:** An isolated language with a unique grammar that is unrelated to any other known language. It has a complex case system, agglutinative morphology, and an unusual verb structure.

19. **Navajo:** A Native American language with a complex verb system that incorporates many prefixes and suffixes to indicate tense, aspect, mood, and other grammatical features. It also has a complex noun classification system.

**Tier 5: Extremely Complex (Requires significant dedication to master)**

20. **Polish:** One of the most complex Slavic languages, Polish has seven cases, complex verb conjugations, and a large number of consonant clusters.

21. **Georgian:** A Kartvelian language with a complex case system, verb morphology, and a unique agglutinative structure.

22. **Dyirbal (Australian Aboriginal):** Famous for its incredibly complex noun classification system, with four genders determined by subtle features. The grammar is very different from Indo-European languages.

**Again, please remember:**

* This is a generalization.

* Individual languages within families will vary.

* "Simplicity" is subjective and depends on the learner's background.

I hope this detailed breakdown is helpful! Let me know if you'd like me to elaborate on any specific language or aspect of simplicity.