Which criteria provides the most stability at sea in a 48-55 foot?

These days, many (if not most) Predators either come with stabilizers from the factory, or are retrofitted with them.
"Inherently stable" is what every boat is, but only when stored on a cradle.
Even catamarans can roll like pigs, depending on conditions.

I understood what you were trying to convey, but I just happen to disagree.
Hull stability is a very specific technical concept, that has very little to see with overall comfort - which I assume is what the OP was actually looking for, when he asked about "the most stable cruise".

In fact, as I'm sure you know, also hulls with a high initial stability do roll in a seaway, eventually.
Leave the "such a good hull that doesn't need stabilizers" argument to boat show salesmen - we all know better, around here.
The difference is that highly stable hulls tend to roll with a snap-back effect, often coupled with a short roll period, that makes their motion jerky and uncomfortable - if not even dangerous, whenever you can't find anything to grab while moving around.
OTOH, hulls with a lower inherent stability will probably roll to a greater degrees range for any given conditions, but their much softer and predictable pendulum-like motion, with a longer roll period, is more pleasant - or less unpleasant, anyway.

On top of that, you are right in saying that hulls with a very high stability benefit less from stabilizers, but that's actually their problem rather than a plus, as you seem to suggest.
Remember, between a hull with a low vs. one with a high roll resistance, it's the former that is easier to stabilize, not the latter.
And that's NOT because the latter wouldn't benefit from stabilization, but because no matter the type of stabilizers used, they will never be as effective as in the former (unless oversized, which opens another can of worms).

In fact, also leaving aside all technicalities, at the end of the day I've yet to hear of anyone going RTW with SFs.
I understand that you like them, and I'm not denying that they have their place, but proper blue water boats they are not.

Yeah, also Buzzi reached Bermuda from NYC with a 41 footer, AVERAGING 40 kts and establishing a new world record.
So what? Exceptions are just that, exceptions - that prove the rule.
Nobody in his right mind would pick an FB 41 - even if way safer, faster, more stable (to the point of being self-righting) and seaworthy than any sportfish - and neither a 63' Hatt for that matter, just for making that sort of crossings for pleasure.

I recommend Florida Nautical Surveyors if you are going to use a Ft. Lauderdale surveyor; I believe they do have a surveyor that lives locally. For the west coast exclusively, I have used Adrian Volney several times with clients who were pleased. However, I have recently gotten a recommendation for Rob Cozen, but that is a 2nd hand recommendation.

Judy