Color neg films have to make huge sacrifices in order to get all their dynamic range, and the sacrifice is density range. That's why strong colors on print film look muddy and it's impossible to get any of the MF/LF 'glow' you see from popular LF film shooters in your own color neg work.
Highly dependant on this is your own workflow, so you should experiment accordingly. If your'e doing your own scanning Astia is the easiest to scan followed by Kodak's Professional-100 series followed by Provia. In terms of color neg films you need to fight through that stupid orange mask which means it all depends on what profile you are using or scanning software.
And this is what it boils down to, workflow and style. The density of slide film and fine grain structure surpass my scanner's ability to capture the needed detail. I often got results that were hazy at 100% with difficult colour casts, that no amount of WB tweaking or USM wrangling would make satisfactory. Colour neg film has the grain structure to create apparent sharpness through accutance, and enough latitude to compensate for field conditions: handheld, on the move, no time to be attaching filters or setting up tripods. I've done an 18x24" from a 645 frame that is satisfactory enough, but my shooting attitude is more laissez-faire and people centric than the focus of this site.
If I had the $3000-10000 to buy a dedicated 120 film scanner (an unsupported nikon coolscan or an imacon), then slide film would be more appealing. But currently I get better and more consistent results from colour neg.
I think for MF colour film, the market better supports C41; in innovation, availability, and cost. It's taken me 3 years to develop my scanning process to improve my C41 results, but colour neg can produce great work if you appreciate its aesthetic... see Bruce Percy's Nepal, India and Morocco portfolios for some great examples http://www.brucepercy.co.uk/pages/Portfolios/portfolioindex.html
However, if you have access to high end scanners and want pure colour fidelity and maximum resolution, then Wseaton's response holds true. I just can't afford that route, and dig the C41 tonality over slides. I shot 35mm B&W for almost 3 years straight, so maybe it's biased me.