Generally, the larger the light-gathering area of the lens (for a refractive telescope) or mirror (reflective telescope) the greater detail you will be able to see, whatever your target.
Very large mirrors are much more feasible than glass lenses of comparable size, so reflective telescopes have taken over from the more familiar refractive design at the forefront of astronomy for some time now. The second-largest earth-bound optical telescopes are the twin, 10-meter, segmented-mirror telescopes of the W.M. Keck Observatory in Hawaii. Here is a gallery of images they have taken of objects within our own solar system, mostly the gas giants, and most in infrared (longer wavelengths of light than red which we cannot see with our own eyes).
A space telescope has a clearer view than an earth-bound telescope as it doesn’t have to deal with atmospheric disturbance. Hubble’s mirror is only 2.4 meters compared to Keck’s ten, but here you can see some nice images of Mars and the gas giants it has taken. By combining multiple images together in a computer, they can even get a very fuzzy picture of what Pluto might look like.
But if you can get the funding, nothing beats sending some good cameras out on a spacecraft for a real close look. For example, here you can see galleries of images captured by the Cassini probe of the major moons of Saturn. And here are images from the Voyager probes.