1D-2D will work well in most situations and it is what I use. It is more traditional, so perhaps more accepted. Bridge modeling will also be much better, since HEC-RAS does not yet allow you to model bridges (i.e., not a culvert) in 2D.
2D would do decent with the channel where you don’t have structures (or the structures do not significantly impact the water surface) and want to do a quick assessment. Or where you want to know detailed velocities and flow paths (for example complex breakout areas or backwater).
Perhaps try both for a small section and investigate the differences. It’s a good learning experience and will show you that even with both setup properly, you will get slightly different results.