One reason to incorporate as a C or S-corp is that it's easy to add 4-year vesting to founder shares. This protects you if your co-founder walks away after 6 months. It's much harder (if it's even possible) to vest "shares" in an LLC.

In your case of a 50/50 split, make sure your agreements also have a clause that deals with disagreements. IT's likely you'll come to a point in your business where you do not agree and 50/50 ownership can make your business stall. Codify how those disagreements are solved before you get there.