The current 'fixie' fashion is for cut down (very narrow) MTB riser bars with long BMX grips and a short stem - preferrably Jap 'Nitto' brand if you're affluent and seriously trendy. What will the fashion be next week? Bar style should be dictated by riding position, and position should be dictated by the use the bike is put to - not messenger lifestyle trends.
I have several SS (not fixie) road bikes. I ride them amongst regular geary club racing cyclists with my local cycling club. I'm usually the only one without gears. To keep up (which I do very well) I need the same aero advantages as my club mates, so I need drops. My bars are dictated by riding position which is dictated by the type of use my bikes are put to. Also, drops give a choice of three very different riding positions - each with a real purpose in proper cycling. Narrow riser bars give just one.
If you just want to pose around town with this week's fashionable bar style, then I suppose gold anodised Nitto risers might be okay. My bikes have substance and are about me actually using them for real cycling - not just posing. Narrow MTB bars would be pretty useless for a 110 mile club run in the company of a bunch of fit club cyclists!
The great thing about SS is that we need not follow convention, and can build a bike to perfectly suit our needs. If your need is for fashion then you'll build a completely different bike to me! narrow risers have become the new convention for fixies - but I'm keeping my drops for SS.
So, there's your first opinionated response!
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"Gears are like eyes or testicles. Having more than one is an unnecessary luxury." Elvis A. Presley