.com, .org, and .net are three old TLDs that are considered general purpose nowadays. I still feel that they have the most "cachet" as well as long-term stability. On top of that, from what I recall when I was looking with a similar question, I found out that many of the other TLDs have much more stringent rules about various stuff that can result in your losing the domain name if you violate them. For instance, .io doesn't allow porn, some others (I don't remember which exactly, but a lot of them) have strict rules against copyright infringement / piracy, and so on and so forth. In the end I decided that .com, .org, and .net were still the best gTLDs for me. They also generally have some of the best pricing for domain names, with a few exceptions.

If you decide to go with one aside from those three (or any of them, really), I recommend researching not only the rules of that TLD, but also the background of the registrars to try to get an idea if they seem like they'll be around for the long haul and know what they're doing.

Edit: I should have said registries instead of registrars above. I also found the original article where I learned some of this stuff about which TLDs offer better protections for domain owners, from the EFF: https://www.eff.org/wp/which-internet-registries-offer-best-protection-domain-owners