Your Preference: Resolution or Fullness?

Gotta do both pretty well and sound good overall. Lots of good affordable gear is capable of both.

The main keys to both together is often getting a good integration with room acoustics and an amp that is 100% up to the task of driving the speakers to the max. Power needed to do this with many modern speaker designs, especially at higher volume levels and with many modern "louder" recordings in particular is often underestimated.

After that is done well, the rest is more or less "fine tuning" the sound. Everything else will have an impact in all ways and no two combos are likely to sound exactly the same, so individual preferences come into play to a large extent, assuming gear is good quality in general.

I don't have to choose. I get both.

If I would choose only one, I choose fullness

I actually agree with the OP's premise - that it's almost always a trade off. More "warmth" in the upper bass ("fullness") tends to obscure resolution in the lower mids to some degree. I also agree with Viridian that tone trumps all.

In my main system, I employ traditional, dynamic speakers from Merlin - which maximize resolution at the expense of (a bit of) fullness/warmth, and Verity - which offer more fullness/warmth at the expense of (a touch of) resolution.

Some A'goners seem to find the Merlins too "lean", but it's rare that I have a problem with their tonal balance. On most material, they're great. Same with the Verity: It's very rare that I'd ever crave more resolution. Yet, side by side, each speaker does illustrate the other's strength and weakness.

Dipoles and omnis can skin the cat a different way. Purportedly, the lightweight drivers of a planar (I own Maggies, too) provide resolution, while the reflected energy provides a sense of fullness. If an omni (eg Ohm) is voiced a little lean, you get a similar effect; resolution fleshed out with reflected energy. Some might argue that the latter (reflected energy) ends up obscuring the former (high resolution direct signal), but IME, that's highly room and set-up dependent.

All three approaches have their appeal, but most often I end up trying to split the baby with the Ohms.

Just MHO.

Marty

"Some might argue that the latter (reflected energy) ends up obscuring the former (high resolution direct signal), but IME, that's highly room and set-up dependent."

I'm in the opposite camp.

Sound (including detail) is a 4-d (including time dimension) phenomenon, not 3 or 2.

Most recordings have spatial cues captured in the sound. I view being able to hear those properly reconstructed (in 4 dimensions) as part of being able to hear the detail effectively. Soundstage and imaging are the things most commonly cited that enable this.

That cannot happen without reflected sound. Try to get a "soundstage" and imaging from speakers set up outdoors for proof. OR from most conventional head or ear phones.

Delivering the sonic spatial cues present as best as possible is ALL about room and setup (also listening position and associated timing between direct and reflected sound) as Marty indicated. This is the case with all speakers, directional, bi, omni, whatever. How to accomplish best with each will vary.

The key is to get the timing of the reflected sound correct correct so that they are delivered accurately. Not addressing this along with all the other aspects of setup is a common problem. Detail will be masked otherwise, more with some recording than others, but to some extent with most all.

Regarding dimensionality and detail, go see a modern visually detailed/exciting movie in both hi res 2-d and 3-d. WHich enables you to focus in on the details as needed better? Same applies to recorded sound.