On the forums because
- other players may read my report and respond to it ("yeah that's happening to me too" or "you're misunderstanding what causes that bug, it's actually..." etc.)
- Someone from ZOS may read and respond to it
- it's easy to link to later ("I reported this here (link) three weeks ago and still no response" etc.)

I do both, but I don't usually duplicate.

For new content related to the Update, I use the forum. This is especially the case where there is a feedback thread for the feature.

Everything else gets /bug, although, if there is a forum thread about it, I might just do some manner of "me too" and add any additional details that I might have.

For pretty much the same reasons listed...

• There is no way to get a back-and-forth with the in-game /bug. Most forum reports are not replied to, but a few are. And sometimes that back-and-forth is valuable, e.g., for clarifying things.
• I can go into more detail on the forums. Attach a screenshot, etc. If I need to go back and edit the report, make corrections, add more information, etc., I can't do that with the in-game /bug.
• Other people can see it and share their experiences, elaborate on details that I may have missed, etc.
• An open public record that can be referenced.

I report most bugs using /bug, but UI and addon related things I prefer to report on ESOUI since other addon authors see them there, we use tags in the thread title to track their state and also because @ZOS_ChipHilseberg is awesome and responds to these posts. Aside from that the ingame bug tool has a very low character limit in the input field which prevents me from adding all the information I want (full stack traces, steps to reproduce, screenshots, videos etc.) and no proper categories for UI errors (not limited to just them though).

If I'm sure it's a bug then I'll /bug it. Sometimes I'm not sure, because we don't always know what the intended behaviour of the game is. For example, with recent Level Up rewards we were only given very incomplete information about what we should be getting.

Regardless of whether I /bug it or not, if I think something might be amiss I always put something on the forums, in one of the official feedback threads if there is one that is appropriate. If I have /bugged it then I put the ticket number in the post. I post screen shots and give more detailed narrative on the forums. Sometimes the /bug dialogue text limit is just too small to explain in sufficient detail what I was doing and what I saw.

I use the forums for the same reasons as @code65536 gives, plus it also acts as a warning to other players if the bug is serious and doesn't get remedied before the update goes live, as happened with the storage chest delete bug in update 17.

I don't always report bugs. But when I do, it is usually about ESO working as intended. --Abraham Lincoln.

I'm more likely to report a bug on the forum if there's already an applicable thread. (I'm not likely to make a new thread about something, to avoid clutter and because I assume someone else probably has or will.)

/bug can and should be an easy thing to whip off when I encounter a small bug in-game, but it becomes more of a hassle than it's worth because a) none of the categories ever seem to apply to the thing I'm trying to report, so I waste a bunch of time looking at category options and trying to decide which one is closest on the dartboard, b) it's hard to get details to include because you can't be looking at the issue at the same time you're typing the report, c) you have to stop what you're doing to go through the whole /bug process rather than screenshotting and typing up a post later, and d) you can't attach the screenshot you just took of the actual issue, and the "take screenshot" option is pointless if the camera has already shifted focus from the issue to you filing your report.

On the forum you can go into a lot more detail, attach screenshots, interact with other players, and see responses and questions from devs. There's also a record there for everyone to see and it's (presumably) easy for the devs to refer to a thread or post that can be linked easily.

It's probably also worth noting that I find the forums very accessible because I'm already a heavy forums user. Someone who doesn't have an active forum account or isn't familiar with using the forum would probably find the in-game feature more accessible.

So I've used both, if I had to state a preference it would probably be forums, but there are definite improvements that could be made to /bug to make it more appealing to use.

Also forum is a funny word if you say it enough times.

I like to report on the dedicated threads, as I feel it is structured and collected in the right place, where other people can react and add some data if they feel it would help.

However it feels like they are not taken into account. Quantity of issues reported on the forums that go live are quite overwhelming. As someone who loves the game I would be very happy to see this improved in the future.

By using the bug thing in Tamriel.

Because this one assumes the pest control people may not read all of the forums all of the time yes - even if they may look at major issues there.

Yours with paws
Santie Claws

On the forum because other players can also see it and provide more information and it is harder to ignore bugs if they are noted somewhere public.

In general the ingame bug report is really not well designed and most of the time you are just wondering in what category the bug goes.

Was the first time in downloaded the PTS.

I reported very few bugs, and very minor ones (scalecaller peak map for exemple). but always both on forum and with the /bug fonction.

This one is sometime quite strange.
I remember using it because i didn't find back a perfect roe in my inventory. The answer i received was "we won't talk about game mechanics". That was funny, but made me sure i was talking to a bot.

As it was said before, forum posts helps us to see if what we experience are bugs, or intentionnal mechanics. (Teso is a pretty complex game, you know ) -> best exemple was the buggy heal from dk's whip. How can one player like me know if it's intentionnal or not?

(and english is not my native language, so following other ppl coments is easier.)

The first thing I do is ask my guildies to confirm if something is good or bad or broken in PTS, so we have time to prepare for it.

Sometimes I don't report bugs in forums purposedly because I don't want more people to know about them and abuse them. I use the in- game report tool instead. (which didn't work for anything so far.)