Region or city of your country with the most correct accent

[nafz]

How different can be the accents within Greece and its islands ? Wich accent do you consider the further away from standard Athenian Greek ?

Quite different I would say.
Northern Greek (Thessaly - Macedonia) accent is more "heavy".
Cretan accent is considered "heavy" too.
Island accent is mostly different in the dodecanese , their accent is close to the Cypriot one.
Ionian islands accent sounds "Italianish" aka singing alike because of the Italian influence there.
The furthest one, I don't know probably the Cretan one when spoken by some of the older native people in the island.

[Sizzo]

^ Ancelotti is from Emilia-Romagna (Reggio Emilia), he has an Emilian intonation so a northern regional Italian. He's from the same area of people like Romano Prodi, Luciano Pavarotti, Zucchero (the singer) or Alberto Tomba.

Speakers from Bologna:

[Sebastianus Rex]

^ Ancelotti is from Emilia-Romagna (Reggio Emilia), he has an Emilian intonation so a northern regional Italian. He's from the same area of people like Romano Prodi, Luciano Pavarotti, Zucchero (the singer) or Alberto Tomba.

Speakers from Bologna:

Yes, definitely the same accent as Ancelotti. They have a peculiar way of pronouncing the S as X or J.

[Mikula]

I am afraid that the "correct Czech" accent exist(ed) just at TV and radio broadcasting, before the 1990s, when appeared commercial stations, there.

[The Blade]

In Bulgaria it is widely accepted that the most correct accent is spoken in Veliko Tarnovo (historical capital of the Second Bulgarian Empire) and Ruse.

[Sebastianus Rex]

In Bulgaria it is widely accepted that the most correct accent is spoken in Veliko Tarnovo (historical capital of the Second Bulgarian Empire) and Ruse.

Is there significant variety and differences between the regional accents? Any accent is particularly hard/different?

[The Blade]

Is there significant variety and differences between the regional accents? Any accent is particularly hard/different?

There are a lot of accents and dialects with some being more common than others.
Most prominent accents include that of our capital city Sofia, the Central Balkan accent (I'm a speaker of this one), the Thracian accent, Southwestern accents (spoken in Dupnitsa, Samokov, etc.) among others.
To me (and many would agree with me) the accents spoken in the Rhodope mountains (in cities like Smolyan and Batak, to name a few) have always sounded the most different. The vocabulary in this region is also quite different and it's very close to that of Russian language (should be noted that this is the region where Slavic influence was strongest historically). As amazing as it sounds, I understand Serbian, which is a separate language, better than this (Rhodope) accent which is spoken in my country.

[Sebastianus Rex]

There are a lot of accents and dialects with some being more common than others.
Most prominent accents include that of our capital city Sofia, the Central Balkan accent (I'm a speaker of this one), the Thracian accent, Southwestern accents (spoken in Dupnitsa, Samokov, etc.) among others.
To me (and many would agree with me) the accents spoken in the Rhodope mountains (in cities like Smolyan and Batak, to name a few) have always sounded the most different. The vocabulary in this region is also quite different and it's very close to that of Russian language (should be noted that this is the region where Slavic influence was strongest historically). As amazing as it sounds, I understand Serbian, which is a separate language, better than this (Rhodope) accent which is spoken in my country.

thanks for the much detailed answered. Lol, it's pretty extreme to understand better a foreign language than a regional accent (dialect maybe?).
In my country I'm sure most agree that the most dificult accents are some Azorean ones (yes there are several distinct accents in the archipelago), but the curious part is the reason for it is because Azores retained many accents that were common in the mainland centuries ago but were lost with time.

[MysteriousWays]

I think for standard American accent, there is a belt running from southern Ohio, through southern Indiana, Illinois, into Missouri, Iowa, Nebraska and Kansas that is probably the most "correct" American English accent. California accent (which does exist, at least to me) isn't bad though either.

Most difficult to understand accent is some Southern American dialects (I'm thinking Ozarks in particular), as well as New York accent for many, and maybe Boston. In general, it's easy to understand most other American accents for me, but I lived in the South for about six years, so that helped with Southern accents (it was more of a coastal southern accent, towards traditional Southern midlands accent).

[ovidiu]

For most countries, isn't the prestige dialect or pronunciation usually based on the region of the capital and/or biggest city? In France a lot of regional dialects and languages were marginalized and largely replaced by Parisian French, for example.