What's better (in terms B&W print image quality), to scan a developed negative and then digitally process and print it, or printing via traditional methods, using enlargers and light sensitive paper?
"Best" is a relative term, depending on your goal(s). :)
If you want the most flexibility (control over relationships between density, contrast, shadow and highlight detail), scan the negative and manipulate it in post-processing. The higher bit-depth you can get, the better for smoother gradations if you'll be making big adjustments in post.
If you're a photography purist, print with an enlarger. You can control highlight & shadow detail through dodging and burning, and contrast through use of multigrade filters. But it's a much more laborious process. Rewarding when you have mastered it, but not easy in the beginning.
One factor you might consider is the added cost of an enlarger, paper & chemistry.
And FWIW, conventional printing will be done on black and white photographic paper, and digital printing will be done on color photographic paper. There aren't enough archival differences between the two to worry about longevity - provided your paper processing is done correctly. B&W papers from various companies have different tones, too. Kodak's is fairly neutral, maybe slightly bluish. Ilford's tend to be warmer (slightly brownish), from what I remember. That may have changed since I worked in a darkroom (close to 20 years ago).
Scanning a negative and then digitally printing it allows for color management, so even if it is a B&W image, your tones will be faithfully reproduced (or can be tuned). You can also remove certain amount of noise, grain, etc.
If you develop the photo, your development method, selection of paper, etc. will determine the end result. Since paper has slightly non-linear response to light (and same is with the negative), plus your exposition time, temperature, etc. can vary, your reproducibility of the original image is worsened.
The only time you would go for paper print if you have a special negative and paper with larger dynamic range than current CMOS sensors in scanners.
Note however that you can rescan the same negative multiple times, and with some filters, you can recreate the film's dynamic range. Moreover, multiple scans and post-processing can help further removing noise.
Flexibility the scan mostly wins.
But that assumes a really good film scanner. A flatbed with a film tray ain't what I'm talking about. Even the decade-ago desktop standard of 4000 dpi was barely good. And the technology hasn't advanced much. I think Plustek has the only current high-res desktop film scanner. Be wary of scanners that may generate a shitload of pixels but don't have the quality optics to actually use said pixels.
The optical print still does better with some edge cases:
Extreme resolution... I've got an optical 16x24 from a 35mm Tech Pan neg that very much outresolves even an honest 6000 dpi drum scan of that neg. But that's perfect film, incredible lens (12mm Voigtlander), perfect exposure. And a top-notch enlarger. And a wonderfully OCD printer (human) I wish hadn't disappeared.
Extreme density... most scanners have trouble seeing into dense highlights. Doubly so dense silver highlights. Enlarger prints can shoulder off a lot more gracefully.