Out of a long list of suggested master thesis topic, how to decide which one to choose? I'm currently doing a master in mathematics, and will start my master thesis in a couple of month. My university provides a list of (suggested) topics. I'm finding it difficult to choose though, since these are my criteria the topic must satisfy:


I must find it interesting/enjoyable.
It must be something relevant/new. This is because I intend on doing a PhD after my masters, and I think it would increase my chances of getting into a good program if my thesis topic is about an area that is still actively being worked on.


These are basically the only two things I care about. However, I do not feel like I'm in a position to determine if a given topic satisfies either of those criteria. 

Most of the topics require a lot of reading before I can understand what they are about, so I don't know yet if I would enjoy it because at the moment I don't understand the topic. Even more problematic is the second point, since I have absolutely no idea which topics are currently considered 'hip' or however one would call that.

So I'm asking what the best way to go about this would be? I realise there might not be a clear cut answer, but I'm looking for some suggestions on what to do here.
Background: while I'm not in mathematics, I have some experience crafting these lists. 

I would not worry too much about it being relevant/new/hip. Usually, thesis topics are chosen so that they have at least some opportunity to be analyzed in a novel way (they peeked the interest of the advisor). I would therefore advise against choosing your own topic, unless you really know what you're doing and what the state-of-the-research is in said topic. 

It is, however, crucial that you are interested in the topic, because this is what will determine whether you'll have the discipline and energy for persevering. You said it was hard to determine this a priori, but I suggest you at least try to get a faint idea anyway so that you can narrow down the list to up to three topics.

Besides interest, it is also very important that you talk to the respective faculty/advisors, in order to make up your mind about with whom you want to work. This may prove to be an even more important point since their support may ultimately be crucial in securing that PhD offer. Additionally, I find that talking to people often allows you to get many clues as to what kind of researcher they are and whether that conforms to who you'd want to be.