Tobacco smoking produces greater striatal dopamine release in G-allele carriers with mu opioid receptor A118G polymorphism
E cigs need to go through the FDA

And according to a 2021 report into vaping from PHE: Smoking prevalence (including those who smoked sometimes or more than once a week) in March 2020 was 6.7% (compared with 6.3% in March 2019) and has changed little since 2015 when it was 7.1% There was little change in levels of vaping over the last few years with current vaping (at least once per month) prevalence being 4.8% in March 2020, the same as in March 2019 Smoking prevalence is at 6.2% (defined as smoking more than 100 cigarettes in their life and having smoked in the past 30 days) Current vaping prevalence is at 7.7% (defined as vaping on more than 10 days in their lifetime and having vaped in the past 30 days) Based on the socioeconomic status of 11 to 18 year olds, the estimates for smoking and vaping prevalence were higher among more advantaged groups in social grades A, B and C1 (7.1% for smoking, 5.3% for vaping) than for more disadvantaged groups in social grades C2, D and E (5.7% for smoking, 3.5% for vaping)

In the end, becoming a non-smoker is still the best and healthiest thing to do and the cheapest, too.
What Sort of Goods Can You Buy Duty-free
However, the act of smoking itself can still become a habit