Oh, nicotine is way worse. It may not harm your health directly, but addictiveness is exponentially worse.

Wikipedia: Caffeine - Dependence and Withdrawal: Moderately physical dependence and withdrawal symptoms may occur upon abstinence, with greater than 100 mg caffeine per day, although these symptoms last no longer than a day

Wikipedia: Nicotine withdrawal: Symptoms are usually strongest for the first few days and then dissipate over 2–4 weeks (…) In a minority of smokers, cravings may persist for years.

Edit: Left out the “Caffeine” in “Caffeine - Dependance and Withdrawal”

Edit to add: Caffeine withdrawal causes you to be annoyed for a day. Nicotine causes real, actual cravings (you know you need nicotine, whereas for caffeine you’re just generally “moody” - most people don’t feel “i need caffeine, now”, and even if you do, chances are, if you run out of coffee and can’t get it within less than a day, the “craving” just stops).

For some, many of whom I know, quitting nicotine is downright impossible due to the cravings. For quitting, toning down is key. Those that quit either relapse momentarily in times of stress (usually for about a week or so), or complain of very strong cravings every few weeks/months.

Additionally, nicotine isn’t the only addictive compound in cigarettes, and from what I’ve heard, vaping, gum, etc. just isn’t it for some - people also get addicted to cigatettes themselves.

Not to mention, vaping causes pneumothorax and all the other alternatives cause some harm as well, although much less than cigarettes proper.