I don't think starting the day with any sugary treats is a good idea, that includes cookies, cake or doughnuts. Something like plain greek yogurt or cottage cheese with fruit, nuts, flaxseeds (for Omega 3), etc. may be a better option.
I'm not an oatmeal lover, but I've heard that steel-cut oatmeal for breakfast can be very healthy, and give energy until lunch without sugar spikes. Problem with sweets, it there's the unhealthy "high" as your blood sugar spikes, and then it's followed by the depressive "crash", which just makes you feel lousey.