River cruise operators can’t build ships fast enough these days. The minute a new vessel launches, it’s sold out. But no matter – another one is usually following hot on its heels. The shortlisted cruise lines in our Best River Cruise Line category don’t do things by halves, either.

Viking River Cruises set a Guinness world record in Amsterdam on 20 March when it named 10 riverboats in one go. AmaWaterways has just launched a new ship on the Douro (named by Sharon Stone, no less) and will break out the champagne again in August for the naming ceremony of the new AmaPrima. Avalon launched two ships last year, two this year and has three due for 2014. The pace is relentless.

So Best River Cruise Line is a hotly contested category and a difficult one in which to vote, too, as the standards on all modern river cruise vessels are so high. Does it come down to facilities on board, like the heated pool with swim-up bar on the new Ama ships? Food, maybe?

Viking’s indoor-outdoor Aquavit Terrace, featured on each of its Longships, is a huge hit for al fresco breakfast and lunch as the ship makes its way slowly along Europe’s great rivers. Or take Uniworld, which has the only restaurants on the rivers to be recognised by the famous Zagat guides. Then again, perhaps it’s the service; the idea of a private butler for every passenger on Scenic Tours’ European voyages is pretty appealing.

Maybe the winner will be the line with the most creative itineraries

There’s a limit to the world’s navigable rivers, of course, but new cruising areas are coming into fashion at a rate of knots. Take the Garonne, in western France. CroisiEurope has just launched a second ship to sail out of Bordeaux, exploring one of the world’s greatest wine-growing areas. AmaWaterways and Viking will both start sailing out of Bordeaux next year.

Uniworld is offering a cruise season on Italy’s River Po this year. Ama is the only operator to offer a safari and cruise combination on the Zambezi Queen in Namibia, while small ship specialist eWaterways can take you cruising in Scotland, Sweden or even along the Amazon.

AmaWaterways, Viking, CroisiEurope, Uniworld, APT and Avalon have between them opened up the Mekong, in Cambodia and Vietnam, over the last few years. And for customers who can’t get enough of southeast Asia, the Irrawaddy is set to be the new Mekong, with Viking and Ama starting cruises into deepest Burma in 2014.

Or perhaps it’s themes that capture the imagination

The River Cruise Line, for example, has a huge range of Christmas markets cruises in Europe, and in summer, voyages to see the dazzling fireworks of the Rhine in Flames celebrations. AmaWaterways continues to add to its wine-themed cruises as they’re so popular, while Avalon offers themed departures covering everything from art to beer, jazz and golf.

Whoever wins this dynamic, exciting category, it certainly will be well-deserved.

Sue Bryant is on the esteemed panel of judges at this year’s Cruise International Awards.

Whether you’re looking for a cultural holiday or relaxing break, find your perfect cruise with our Cruise Finder.