what would be more benificial aircraft engineer or a automobil engineer

Just by the numbers, there is one company (Boeing) in the US that makes planes. New plane designs take decades to finalize and there less than 10 types (737, 747, 777, etc.) There are 3 major car companies in the US, they have multiple brands and models and issue a new model each year - just by numbers there are more jobs in auto. That said aerospace can demand higher salary but the competition for those jobs is much higher. As the saying goes "There's no free lunch." The scarce jobs demand high salary but more people want them so it's harder to get. It's just like college, Ivy league schools only have so many spots so they reject more students than public university but if you get in you reap big benefits.

But your question also made me think about your point that you want the most money. I know that it may seem to you know that whatever gets you more money is the better option but I urge you to reconsider that mind set. Yes money makes a difference but there is a point where it won't matter as much. Engineer is a career (not a job) and if you stay on this path you will do well as you advance. We all have different levels but there have been numerous studies that show the "tipping point" where more money does not give you more satisfaction. Once you can afford a nice place to live, a good car, some savings to weather emergency spending and extra money to do fun stuff (vacation, go out to eat, movies, concerts, etc) having more money may allow you increase the quantity of the stuff but usually doesn't equate to same increase in satisfaction.

As an easy example, the difference in making $25k vs $50k is huge, and $50k vs $100k makes a real meaningful difference but $150k vs $100k gives you more options but probably has less impact. So when you're thinking of a career path - salary is important but when your choices get you to similar positions, things like what you are working on (do you love cars and think planes are just ok), who you work with, the variety of work you do (one plane vs 10 cars over 10 years) and things like that start to drive your happiness and satisfaction much more.

Either way, I think getting into engineering is a great career choice and wish you the best of luck. And don't sweat some of these choices too much. I'm nearly 20 years in to my career and I never would have thought I would end up where i did. In fact, while I was in college, I used to say I would never work for a large company yet here I am. And I don't regret any of my choices - I trusted my instinct, set wide goals for myself (be a CPA, manage a larger team, be part of large scale project implementations) and followed interesting and fun assignments that I thought would teach me something and I would enjoy.