Caves or tents?

Difficult. My most memorable overnight stays have been in a tent.You can choose how far away from water and how close to the escarpment to set
up camp. Plus after spending one night in the dust and black residue found in Crows
Nest Cave made me prefer tents.

There are a number of variables that comes into play when trying to determine which is better. Here are some factors for and against each I normally consider:

Pro tent arguments:

1. Tents are enclosed, so you are generally better protected against the elements (wind, rain etc. - except if your tent leaks, of course ) than you would have in a cave, like in a shallow overhang   However, being enclosed means you often has less of a view
2. Tents are clean - no soot or animal dung to contend with as in caves
3. Warmer - no freezing drafts in winter
4. You can erect your shelter anywhere, anytime. In case of sudden bad weather, or an injury in your group, you are sorted
5. Allows you more freedom to move around in the berg, and set up shelter anywhere, typically close to water. You determine how far you want to hike for the day, not the availability of shelter
6. You get to spend cash on cool gear

Pro cave arguments:

1. More space. Think Xeni cave which is about as large as a school hall. At 1.97m tall I can't find a tent long enough that my feet doesn't touch the bottom somewhere
2. More secure. Thiefs and robbers can typically only enter on one side, offering you better protection. For instance Rolands cave, where I seriously doubt a thieve will come to steal your socks and boots at night
3. Weight saving. No tent to carry up to the escarpment
4. More social, as you don't have any barriers between you and your fellow cave dwellers
5. Lots of fresh air available, and sometimes a bit of mist and some spray from wind blown rain 
6. Quite often very dramatic settings - like Ledges, Rolands etc. Definitely more adventurous walking into Rolands than climbing into your tent.
7. You are more in tune with nature

At the end of the day, the reality is that you will most likely use both. Each has their specific role to play in your hikes. Even if you only want to sleep over in caves, the reality is that they may be occupied, of you can't find it in thick mist or somebody in your hiking group gets injured etc. and you can't get to the cave, then what? For the 'then what' it is always a good idea to carry some form of shelter, if not a tent maybe a bivvy, survival bag or tarp.