I would opt for the latter of your two suggestions. The first is just too verbose, and your paper will lose readibility for what little it gains in deference to their titles.
The committee finds that Professors X, Y, Z have contributed to the area.
I would amend slightly to
The committee finds that Professors X, Y and Z have contributed to the
This is following the suggestions for citation from Harvard Referencing (see 'In-Text Citations for Two or Three Authors', towards the end of the page here), when you are referencing in text citations for two or three authors. Although in this case you are not actually citing their body of work but referring to their general contribution, I would say this would give you excellent justification for using this construct in your particular example. Granted the referencing scheme does not refer to titles specifically, but this is a guide to referencing for academic papers, if there was some kind of need to qualify each of the individuals with their named titles I am sure it would have been articulated in the guide.
On the subject of deference you are acknowledging each of them equally by using the plural of 'Professor' and then listing them as you do. Grammatically the noun is shared with each of the named individuals.
Also as I say from a pure readability standpoint, the second of your two options is far better (just with the conjunctive 'and' before the third professor).