Stirring and tuneful as many of the world's national anthems are (including my own country's of course!), I'd give the gold medal to France for the Marseillaise.
The composer of the Marseillaise was one Claude Joseph Rouget de Lisle (1760-1836). Rouget de Lisle was, somewhat ironically, a royalist and was imprisoned a year after writing the Marseillaise, coming close to being guillotined. He was released after the Thermidorian Reaction, when the Reign of Terror came to and end and its architect Robespierre got the chop. 27 July 1794 was the day when things kicked off. In the French Revolutionary Calender that date was 9 Thermidor, an II de la République. Rouget de Lisle quickly set pen to paper and composed his Hymne Dithyrambique sur la conjuration de Robespierre et la Révolution du 9 Thermidor and presented it to the National Convention. He was a survivor. (That piece isn't to be confused with the Hymne pour le 27 juillet (Chant du IX thermidor) by Jean-François Lesueur).
Berlioz, having arranged the Marseillaise in 1830 in the wake of the overthrow of Charles X and the rise of the Citizen King Louis-Philippe, turned his hand to arranging Rouge de Lisle's other hymn. The Chant de neuf Thermidor was the result.
I think it's wonderful - a stirring, tuneful beauty of a piece. Yes, it's a second pressing from the same template ('the same old song'), using a very similar structure to the Marseillaise, but the tune is new - and what a tune it is!
A lot of the credit must go to Berlioz for his superlative arrangement. Scored for tenor (or soprano), chorus and orchestra he fleshed out the accompaniment and turned it into a strophic piece that is worthy of comparison to the Marseillaise - and into a piece that sounds like undiluted Berlioz!
The work was never published during Berlioz's lifetime; indeed, it only saw the light of day again in 1984. (Yes, 1984!) What a piece the world was missing!