For cruisers, belt-drive bikes are easier to customize than shaft-drive bikes (that is important to a lot of cruiser owners, apparently 
Personally, I prefer EFI over carburetors; EFI is supposed to give better fueling and thus better fuel economy. But I have to say that the Ninja 250 I once owned had a smooth reliable motor, and it was carbureted. The two bikes I currently own are both fuel injected.
Whichever bike you get, just make sure to use a fuel stabilizer if you let it sit for any length of time.
Personally, I prefer EFI over carburetors; EFI is supposed to give better fueling and thus better fuel economy. But I have to say that the Ninja 250 I once owned had a smooth reliable motor, and it was carbureted. The two bikes I currently own are both fuel injected.
Whichever bike you get, just make sure to use a fuel stabilizer if you let it sit for any length of time.