You have two opportunities and risks with either. Without knowing specifically what you have in mind, it is difficult to tell you which is better. The answer is dependent upon the terms used or the resulting domain name when whole terms are not used and the performance of the site once created.
I can at least tell you this.
Search engines use ontologies which are databases for a variety of functions such as understanding terms, sentence structures, translation, relating facts, etc. The most basic of these are dictionaries and thesauruses. These have existed since the early to mid 1970s and possibly even earlier. Often within search engines, these ontologies are very extensive and some updated automatically using AI machine learning, and corroboration to understand new terms and their usage.
One of the three original highest value semantic clues that Google recognized was the URL/URI. The full URL/URI is broken into 4 parts; the domain name, the path, the file name, and parameters ranking in importance from left to right. This means that one of the most important semantic clues for what a site is about is the domain name.
Semantics is, at the very least, linguistic analysis to understand the written word. Semantics does recognize full terms using an ontology, however, cannot understand anything that is not in an ontology. This allows search engines to understand a domain name made of full terms rather easily and apply a score to the limited semantic analysis that a domain name can provide. What is important to know is that elements of a webpage including the URL/URI are given a score boost according to value and importance. In this, we already know that the domain name is the most important semantic clue for what a site is about and therefore the domain name is weighted more heavily than almost any other element. This changes only slightly when applying semantic analysis to the title tag on a page by page basis.
For any domain name that is not comprised of terms, the only way that the domain name can gain value is to become a recognized brand. Without getting into the details of branding which is a large enough topic in of itself, branding a domain name is difficult and requires significant signals to begin to move the needle toward inclusion as a recognized brand. Brands are stored into an ontology which once entered, can contain the same value as any term within an ontology.
Of the two scenarios, the fastest and simplest way to have value in a domain name is to use whole terms that exist within an ontology and easily recognized. The caveat I would add is that these terms must effectively signal the topic of the website using semantics in a way that is congruent.