In general i think sales reps make more money overall but have a much more stressful job and can get axed whenever they underperform for a quarter etc
Engineers can also be axed at any time for performance. They're fortunate that most companies are bad at measuring that, but they're also subject to things like stack ranking at very bad companies (fire worst 10% every year) so it's certainly not better to be in eng rather than sales.
Ultimately all roles have aspects of them that suck, so you need to find the one that sucks least for you.
Of course all roles have aspects that suck. But for me FTE is so much less stressful than sales - but I make less money. alas