Creatine monohydrate definitely confers benefits which aren't insignificant. Ignore anyone dismisses creatine. It has plenty of research behind it. I've never had any success with any form of creatine that isn't monohydrate, and I suspect they're all gimmicks. The biggest downside to creatine is some bloating, but i think it's worth it.
Protein is a must, but I wouldn't call it a supplement.
I do make my own daily preworkout by just buying beta alanine and l-citrulline:malate in bulk and dosing it out properly. For caffeine, either those little mio caffeine shots or an espresso shot right before working out.
Vitamins are important for general health, though I only take Vitamin E.
Post and pre-workouts range from either good to just a waste of money. The only good pre-workout that I can notice effects from is C4, while post-workouts are a gamble.
I usually just get my protein from Builder bars.
It also may be important to note that products with creatine aren't vegetarian friendly.