My vote in the Ellora-Ajanta "dispute" clearly goes out to Ajanta! Although the size of Ellora obviously shows more rock carving craftsmanship, I fell for Ajanta's lovely location at a cliff overlooking a horseshoe-shaped bend in the river. And for the quality of its paintings of course.
The colours in the paintings have survived the ages pretty good, although there is a yellowish glow over most of them. Local, natural dyes were used, and blue (lapis lazuli) was imported from Central Asia. Some of the caves, notably 1 and 2, have their walls and ceilings completely covered with these paintings, showing various Buddhist scenes including animals and people.
Other favourite caves include numbers 10 and 26. They resemble the Music Hall at Ellora, with the formerly wooden ribs at the ceiling and the decorations all-around a central stupa. Cave 26 also has a great carving of a reclining Buddha.
I visited Ajanta on a tour from Aurangabad. They leave daily (except Mondays when the caves are closed) at 8.30. You can buy tickets from several organizers, but will all end up on the same bus. The drive out there is 2.5 hours (100km, at 40 km/h about an average speed in India). An English-speaking guide is included. As always on tours like this, the site visit is a bit rushed. But the tour was OK in general. It is also easy to get to the Ajanta Caves by public bus, they leave from platform 6 at the Aurangabad bus stand (buses to Ellora leave from platform 8).