I was a fan of both when I started looking into it buying one. Then my wife expressed more interest in the sedan, and since there was more room in the sedan, that's what we opted for. A month or so later, I saw a hatchback in the parking lot next to mine and started wishing that I had bought the hatchback.
Turns out, my wife ended up needing to drive more for her work, so "my" Sonic ended up becoming "her" sonic, and I got the gas guzzling SUV. That made me appreciate having had the sedan (or any Sonic for that matter).
Fast forward a few months and the SUV starts having some major (read $2000+ issues), so I start looking for a replacement vehicle. Having already done a ton of research, the Sonic was already at the top of the list for a replacement, but I test drove and researched a few more options. A month or so goes by and they announce the RS trim for 2013 which seals the deal for me. Since it only comes in hatch, that made the decision simple. Once they arrived at the dealership, my deposit kicked in and long story complete - we own a sedan and hatch.
Here's my take on both.
The hatch has a more sporty look and feel. The stance appears more planted, the rear lights have a more unique look, and the rear doors are almost hidden - giving it a more coupe appearance. If you don't have rear passengers, the rear can be configured to store a lot of gear.
The sedan while still quick and nimble, has a more practical and refined appearance. There are less risks taken with the lines, and seems to appeal to a more conservative mindset. Storage is similar to the hatch since both seats fold flat, loading the trunk and cabin is not nearly as convenient as having that 5th rear door and there is more total storage with the hatch. However, a real benefit of the sedan is that if you have a need to tote around rear passengers, the trunk storage is still quite plentiful for strollers, boxes, random gear, etc. Whereas, with the hatch, once you have rear passengers, you are limited in what you can tote inside.
