If you want to continue your doctoral studies, that is, do theoretical research, then choose Uni to study, so it will be easier for you to take a doctoral degree after your master's degree. If you graduated from FH, it is more difficult to continue studying for a doctorate at Uni than to graduate directly from Uni, but it is definitely not impossible or difficult, mainly depending on your academic performance and projects you have done. Professor Uni will check your things. If you get good grades and communicate smoothly, you can of course enter Uni to study for a PhD.
If you go to other countries to study after graduation, you won't have these problems. You have gone to study for a doctorate according to the requirements of other countries. Other countries don't understand the German system and won't distinguish between them. Just apply normally.
Therefore, it depends on whether you want to work or study for a doctorate after graduation. If you want to study PhD, you should choose Uni. If you want to graduate quickly and then go to other countries to study for a doctorate, you can choose FH. If you are FH now, study hard and get good grades, and then apply for Dr. Uni.