Are they? To me it seems obvious that if one is seeking those emotions actively, then one will be disappointed or worse if they prove unattainable.

For whatever reason, be it psychological or physiological, it is clear that humans cannot maintain a perpetual high. The serotonin is expended, the stimulant wears off, unhealthy dependencies on emotional states are created. An even keel is worth any number of highs in my opinion. The goal should not be an emotion or a high-water mark, but rather to make progress. Progress is tangible, you can hang your hat on it and be proud of it, and most importantly it's available to you no matter how poor your circumstances or station in life are.

Happiness is found by peace in your own reflection. Be happy where you are, with what you have, with who you are. It's not attained by anything further than this. Arousal feels good, but that's not happiness. Thrill feels good, but it's not happiness. These things are distractions, like drugs, hobbies, work. Happiness is contentment within the moment and delight in what the moment brings.

The issue is that 'Better' is a subjective term.

I don't enjoy wild swings of emotion and the loss of control that often accompanies; so level-headed and clear thinking are better for me.

They feel better in the moment, but result in dumber decisions. So they're a lot like alcohol.