There are many dimensions to consider when choosing a martial art and it may be wise to try a few if you never had experience beside fencing. I practiced Karate (shorin-ryu) for three years when I was young and I was never really happy. I've been doing flying white crane kung fu (fujian, not tibetan style) for many years now and I love it. It just depends on each person. Some dimensions to look for:

Soft (use the opponent strength) vs Hard (punch and kick hard!)

Traditional (deep historical background, traditional forms that have been taught for hundreds of years, at least some sparring without any equipment, spiritual dimension) vs Modern (sparring is almost exclusively done with equipments, more acrobatic moves)

Martial Arts vs. Combat Sport. I don't want to get too much flak on this one, but IMHO, the more rules you have, the more it looks like a combat sport. Which is perfectly fine if this is what you like!

Each school will favor some of these dimensions over the others, even among the same style (e.g., karate, kung fu, and even boxing vary widely across schools).

But the most important aspect is probably the teacher. If you are afraid of your teacher, if you are stressed every time you are on your way to the school, it won't do you any good, because clearly, you are not going there to become the next Bruce Lee or to learn how to save your family from burglars.