There are pros and cons to each.
From what I’ve seen, though, I think that a good digital camera scan setup will outperform Epson scanners for 35mm film (in terms of resolution and sharpness). And once you get a setup you like, it is much much faster (I can scan an entire roll of 135 film in about 2 minutes with my digital camera setup… it may take almost this long just to scan a single frame on my Epson 600).
When it comes to medium format 120 film, though, you may need to shoot a stitch multiple scans with a digital camera to match the sharpness of a good scanner. And stitching together multiple shots can be a real pain and result in distortion. Although, I find for most uses, I’m OK just taking a single shot on the digital camera setup of the 120 film, even if I sacrifice a little detail.
The other advantage of a good scanner is having ICE to remove the dust. I’m pretty careful with my film, so I usually end up with very little dust, but for some situations ICE will be a big advantage.