Originally Posted by rat fink

I would use bullhorns first, followed by the flat bar. Reason being, you might change your preference after a while, and it's easier to transition from a bullhorn to a drop bar.

In an attempt to explain the road position, consider the following:

I come from a mountain biking/motorcycle background, and on an mtb, I like slack angles and a rearward position, but on a road bike, I prefer the speed skater/downhill skier position. It may feel off at first, but you may quickly realize why the vast majority of regular road riders prefer that position.

One thing is that the terrain and environment does not require it. Generally, in the road discipline, one does not encounter as steep of hills (down or up), you are likely to take tighter turns at higher speeds, there is very little air to be gotten, and you ride longer distances at one time. Because a road bike can turn a tighter turn on flat ground at speed, you may also see how important it is to get good bit of weight forward and lower your center of gravity. Most road bikes feel much more stable this way.