Learn Hardcore Turkish: Otobüsü beklemektense yürümek daha hızlı. - Rather than waiting for the bus, walking is faster.

bekle-: verb stem (wait)
-mek: infinitive/verb-noun
-ten: ablative (-DAn) becomes -ten after a voiceless consonant and with front vowels (consonant/vowel harmony)
-se: conditional/contrastive element (ise), here fusing to give the meaning rather than

So otobüsü beklemektense = rather than waiting for the bus. This clause sets up the thing you prefer less; the main clause states the preferable option, often with daha to make a clear comparison.

Why is otobüsü in the accusative (-ü)?

Because beklemek takes a direct object in Turkish. You wait something, not wait for something with a preposition. The accusative -i (here surfacing as -ü due to vowel harmony) marks a definite/specific object: otobüsü beklemek = to wait for the bus (the specific bus you have in mind).

Can I say otobüs beklemektense without the accusative? What changes?

Yes. Otobüs beklemektense means rather than waiting for a bus (indefinite, any bus). With otobüsü, it’s definite (the bus we’re expecting). Both are grammatical; choose based on whether you mean a specific bus or any bus.

Why not use the dative otobüse like English uses for in wait for?

In Turkish, beklemek selects a direct object, not a dative complement. So otobüsü beklemek is correct; otobüse beklemek is ungrammatical.

What is yürümek doing grammatically here?

Yürümek is an infinitive (a verb-noun) functioning as the subject of the sentence. The predicate is daha hızlı. So literally: Walking is faster (than waiting for the bus).

Do I need -dır in daha hızlı? Should it be daha hızlıdır?

The copular -dır is optional in the simple present for general statements.

Yürümek … daha hızlı is natural and common in speech.
Yürümek … daha hızlıdır sounds more formal/emphatic or written.

Both are correct.

Why use hızlı and not hızlıca?

hızlı is the adjective fast and also serves adverbially (e.g., hızlı yürümek = walk fast).
hızlıca means quickly, but in comparisons you normally say daha hızlı, not daha hızlıca. The predicate here is adjectival: Walking is faster.

What role does daha play? Can I drop it?

daha marks the comparative more, i.e., faster. Without daha, hızlı just means fast, not faster.

With daha: Walking is faster (than …).
Without daha: Walking is fast (not a comparison). If you want to avoid a comparative and just express a preference, rephrase: Otobüsü beklemektense yürürüm (Rather than waiting for the bus, I’ll walk).

Can I move the parts around? What word orders are natural?

Yes. Turkish is flexible with word order. All of these are natural:

Otobüsü beklemektense yürümek daha hızlı.
Yürümek, otobüsü beklemektense, daha hızlı.
Yürümek otobüsü beklemektense daha hızlı. Keep daha immediately before the adjective (hızlı). Commas around the -mektense phrase are optional and stylistic.

What are other common ways to say rather than/instead of in Turkish?

-mek yerine: Otobüsü beklemek yerine yürümek daha hızlı.
-eceğine/-acağına (subject-linked, often with a personal nuance):
- 1st person: Otobüsü bekleyeceğime yürürüm. (Rather than waiting for the bus, I’d walk.)
Comparison by reference: -meye göre: Yürümek, otobüsü beklemeye göre, daha hızlıdır.

Is beklemektense the same as beklemekten ise?

Yes in meaning. -tense is the fused form of -ten ise. You can write beklemekten ise (more formal/explicit) or the more common fused beklemektense. Pronunciation and meaning are effectively the same here.

How do I flip it to say Waiting for the bus is faster than walking?

Say: Yürümektense otobüsü beklemek daha hızlı. Here the -mektense attaches to yürümek: yürü-mek-ten-se (rather than walking), and the main subject becomes otobüsü beklemek.