Rather than try to rank Vienna's museums against each other, it's more useful to match them to what you actually want to see — the city's collections don't overlap as much as you'd expect, so picking two or three with genuinely different focuses beats trying to squeeze in five that cover similar ground.
If you only have time for one
Make it the Belvedere, for The Kiss and the strongest single collection of Austrian art from the era most visitors associate with Vienna. It's also one of the more manageable major museums to see well in two hours.
For Old Masters and antiquities
The Kunsthistorisches Museum is the heavyweight choice — the world's largest Bruegel collection, plus Titian, Rembrandt, Vermeer and Habsburg antiquities. Budget a proper half day if you want to see it well rather than rush it.
For drawings, prints, and a broader modern collection
The Albertina covers both — a historic graphic art collection plus a strong Monet-to-Picasso modern painting collection, in a museum that's genuinely possible to see well in under two hours.
For Klimt and Schiele specifically
Split between the Belvedere (Klimt's The Kiss) and the Leopold Museum inside the MuseumsQuartier (the world's largest Schiele collection) — visiting both gives the fullest picture of Vienna's turn-of-the-century art scene.
For something different from painting
The Natural History Museum, directly across from the Kunsthistorisches Museum, and the Technisches Museum (Technical Museum) are both strong options if you want a break from picture galleries, and both work well with kids.
Local tip
Don't plan more than two major museums in a single day — even efficient visitors tend to hit a wall of fatigue after that, and you'll enjoy the second museum a lot less than the first.
Frequently Asked Questions
What is the most famous museum in Vienna?
The Kunsthistorisches Museum and the Belvedere are the two most internationally famous, for very different reasons — Old Masters versus Klimt.
How many museums should I visit in one day in Vienna?
Two at most. Vienna's major museums reward unhurried visits, and fatigue sets in quickly if you try to pack in more.