Is Chinese easier than Cantonese?

Does Cantonese have tone sandhi?

Very little, and much less than Mandarin. This is one point where Cantonese is kinder than its reputation.

Tone sandhi means that a tone changes automatically because of the tones next to it. Mandarin learners meet it in the first week: two third tones in a row turn the first into a second tone, so 你好 nǐ hǎo is pronounced ní hǎo, and 不 bù and 一 yī shift depending on what follows. In Cantonese the six tones are essentially stable in connected speech. You pronounce each syllable with its dictionary tone and you are right almost every time.

What Cantonese has instead is the changed tone, 變音 bin3 jam1, often written "pinjam" in English. It is not triggered by neighbouring sounds. It belongs to particular words and meanings, often with a familiar or "small thing" flavour, and it turns a lower tone into the high rising tone 2 or, less often, the high level tone 1. In Jyutping the change can be written with a hyphen:

Word	Dictionary tones	As spoken	Meaning
糖	tong4	tong4-2	tong4 is sugar; with the changed tone it means a sweet
耳環	ji5 waan4	ji5 waan4-2	earring
今晚	gam1 maan5	gam1 maan5-1	tonight
廣東話	gwong2 dung1 waa6	gwong2 dung1 waa6-2	Cantonese (the language)

Because the change is tied to the word, you learn it as part of the vocabulary, much as you learn which English words are stressed on the first syllable. Good dictionaries and Jyutping materials simply list the spoken form, so 廣東話 appears as gwong2 dung1 waa2.

One more detail concerns the high tone. Tone 1 can be pronounced high level (55) or high falling (53). In Hong Kong the two have merged and the level version is the usual one, so learners can treat them as a single tone. Older descriptions of Guangzhou speech keep them apart and describe the falling version levelling out before another high tone, which is about as close as Cantonese comes to Mandarin-style sandhi.

What this means for the comparison

Kungfucius's view is that the tones themselves are not what makes Cantonese harder. Six stable tones against four tones with sandhi rules is a fairer contest than "six against four" suggests. Mandarin remains easier for the reasons in the short answer: one standard romanisation, far more material, and a written language that matches the spoken one. Cantonese learners should choose Jyutping early and stay with it.

If you are deciding between the two, see Chinese vs Cantonese. Mandarin's own tone rules are explained under Chinese tones.