@鄭宇佋 A less biased answer would be - they aren't entirely equivalent, and the choice is a combination of specific needs and preferences that IMO can't be generalized to "x is better in general".
phpBB is the oldest forum, and as such it embodies the older style of forums from before social media made things like tags, real time interactions, feeds etc. popular. However, it is probably the most feature rich of all offerings if you have time and knowledge to set it up.
Flarum (and I think the Laravel community software too? Never used it :V) is a simpler forum that is tag-based. You can nest tags once in Flarum, but only once and it seems to more encourage a feed approach where your main page is filled with topics sorted in some way and you use tags to go somewhere if you're looking for something specific. This is in contrast to the "classical" structure I mentioned, where you will have subforums/categories that you can infinitely nest and the idea is that the user first goes to the category that will have the topics that will be interesting to them.
However, NodeBB and Discourse are both somewhere closer to the middle, but on the opposite sides. In both you will find categories and tags, but from what I've seen the emphasis is different - NodeBB is categories that can have tags, Discourse is tags that can have categories 🙂
Of course, there are a lot of other differences. As mentioned, more modern software is better at doing stuff real-time. Notifications, chats (Discourse and NodeBB have some form of private conversations built in. Flarum and phpBB have extensions that add it), loading new posts without reloads etc.
AFAIK NodeBB is the only one of these using WebSockets (socket.io)
Discourse uses some custom polling based protocol.
Flarum actually doesn't do much live stuff by default (just kilke phpBB), but it does have notifications that can use officially-supported pusher extension to work.
One major difference though - phpBB, Flarum and Laravel.io are PHP-based, so you can make them work on generally cheaper shared web hosting, meanwhile Discourse and NodeBB will require a server that can run Ruby or Node respectively - for example a Linux VPS.
Which one is better depends on what you want then.
Laravel.io seems to be most limited in terms of customization, unless there are some undocumented features on that front. So if there are any things you don't like about the way it looks or feels - don't choose it.
If you like the Flarum tag structure and don't mind it lacking some things (well, it's a beta after all), it seems like the most performant option.
phpBB? If you are willing to buy/develop some modern theme and spend time to configure it, sure. Otherwise I wouldn't recommend it.
The decision between NodeBB and Discourse is harder, and while I prefer NodeBB, I'd say it's mostly down to your preferences, specifics of what you want to use the forum for and the preference for technology stack (Node, Express, MongoDB/Redis/Postgres + no major js framework outside of jQuery on front-end for NodeBB vs Ruby on Rails, Postgres + Ember.js on front-end for Discourse).
Some unfortunately older topics on this (some will have much more recent replies, so might be useful to read them; I tried to include topics from meta-forums of other forum software and user forums based on software in question):https://community.nodebb.org/topic/1835/which-is-better-nodebb-or-discourse https://community.nodebb.org/topic/10827/why-i-chose-to-use-nodebb-over-phpbb-discourse-mybb-and-other-forums https://discuss.flarum.org/d/2056-flarum-vs-nodebb https://discuss.flarum.org/d/6952-how-is-flarum-different-from-discourse-and-other-forums https://discuss.flarum.org/d/676-what-are-the-advantages-of-flarum-over-discourse https://meta.discourse.org/t/which-is-better-discourse-or-flarum/71726 https://what.thedailywtf.com/topic/23993/nodebb-vs-discourse-showdown (just for context - this forum migrated to NodeBB from Discourse in 2016) https://gamingexodus.com/t/nodebb-current-forum-vs-discourse/employee monitoring (here there was a migration in the opposite direction in 2018) https://www.reddit.com/r/webdev/comments/415nlp/discourse_flarum_nodebb_oh_my/ https://forums.linuxmint.com/viewtopic.php?t=231767&start=20
Obviously remember that the answers will be biased essentially everywhere - here, towards NodeBB. On Discourse forums, towards Discourse. On Flarum - towards Flarum. Etc.
Oh thanks, so much useful information for me as for newbie 🙂