Combination Washer-Dryer

Reviews are positive in general [1]
Drying issues - some are user error, others it works flawlessly
Great pluses: 1200W, water saving, superefficient, actually saves time with longer cycles because you simply walk away and don't have to move the clothes to dry. Space saving. And no vent! Condenses the water.

Dryer Only

Says condensing dryer is faster, but heat pump dryer is more energy efficient
Only 2% of the households have them.
Conclusion: if you want speed, get vented, if you want energy efficiency, get ventless.
But - combining this with washer in one - if you want efficiency and speed (you just walk away, no transfer of wet clothes needed - so active washing time on part of the person is reduced) - then get the combo ventless. Half the work! Perhaps even less than half: half the trips to the washer, and you don't have to move wet clothes.