Either would be easy to say but, I have heard /nais/ on television...

I'm a native English speaker from Europe (you don't give options for native speaker of which languages, but I assume you're only after native English-speaking opinions). I've never heard the /nʌɪs/ pronunciation. I've only ever heard (an approximation of) the French pronunciation of the name of the city used. Gawd knows we Brits bastardise the pronunciation of some of their places, famously Paris (Parriss rather than Paree), and a lot of names of places visited by the army during war were given non-native pronunciations (Wipers for Ypres), so it might be that the army or, more likely, navy developed a /nʌɪs/ pronunciation, but I've never heard it used seriously (except by a young child who had only seen the word written and never heard it said).

That's my non-scientific impression!

If you don't mind saying, in which country were you taught the /nʌɪs/ pronunciation? And roughly when? That's interesting.

Wiki sais so:

https://de.wiktionary.org/wiki/nice

No, but the Wikipedia says, it's pronounced niːs : https://en.wikipedia.org/wiki/Nice

:D i know, @rasmus

I'm french and it's niːs :-)

i 'm french and i confirm what Framasky says it IS ni:s, so no need to vote ;)

The vote is more to see how people say it, even if they say it wrong. The correct is indeed ni:s.

There is definitively but one French way to pronounce “Nice”, and it is /niːs/. Now, when said in a different language, whatever the name is, it always tends to be said differently than in the native language. So, I guess the right way to pronounce “Nice” is the way you do not get confused with the English words “nice” and “niece”, whatever this way may be.

Oh! By the way: I am a French native speaker from France, but it does not change anything.

Oh, wow. Thanks for all the comments. :)

(you don’t give options for native speaker of which languages, but I assume you’re only after native English-speaking opinions)

Yes, I thought that was clear from the context. Sorry, if it wasn't.

If you don’t mind saying, in which country were you taught the /nʌɪs/ pronunciation? And roughly when? That’s interesting.

I am from Germany and it must have been in the early 2000s. (In English class of course.)

I’m french and it’s niːs :-)

Je ne parle pas de Française -- and just so you know I am not lying, I am not even looking up the correct spelling and just leave it as I remember it. ;p

The German pronunciation would be ˈnɪtsaː, by the way. Like Pizza with an N. Yes, seriously. (It's also spelled Nizza.)

Yes, italians also say Nizza - like pizza with an N. Simple as that. Comes from latin town Nicaea.

Ok lol, I heard it called Nice and Niece on TV, which one is it?? An old American here... I was stationed in Germany for 2 years 1971 and 72. Came back to the US with a German "slang"

Rasmus, it actually comes from the ancient greek town of Nikaia (meaning victory) - which later became Latin town. In Greek we actually still use the Greek name Nikaia when referring to Nice.

Great, thanx.

I heard it called Nice and Niece on TV, which one is it??

I now tend to /niːs/. Vox populi has spoken. :)

An old American here… I was stationed in Germany for 2 years 1971 and 72. Came back to the US with a German “slang”

Cool. What kind of slang?

LOL Jan P, I sounded like a German even though I was speaking "english, or American"