Objectively, Equifax is currently the worst.
Anecdotally, I remember the days when you could call Equifax up and just ask them to delete each of your inquiries. - Those were the days when Equifax was all fun.
Lately, Equifax cannot seem to refrain from losing data, whether it be split files, or outright data loss.
They also cannot seem to complete disputes timely; and they'll give you the runaround if you try to dispute any inquiries, anymore.
Also, their Personal Solutions website has been the most sluggish of the three, for almost a decade running, now. - With all sorts of glitches when dealing with their products.
Trans Union would have to be my first runner up, behind Equifax. They also seem to have several online issues, over the years. - Locking people out from online access, arbitrarily, and what not.
Incidentally, I also remember when Trans Union was my personal favorite. They would delete literally anything and everything, just like clockwork. But, eventually they changed, and then became completely unrecognizable... and started balking at anything and everything.
The most scurrilous thing I've seen from any credit bureau is when Trans Union will simply refuse to address a consumer dispute. I've even tested this with multiple people I've assisted, and Trans Union is like the, "Great Benefit," (Rainmaker) of credit bureaus. Deny all claims, and in many cases, consumers have to file with the CFPB in order to get Trans Union to comply with the law.
Experian, is not all fun and games either. But, in my experience, they are the most all around fair credit bureau to deal with... once you understand their innerworkings. - There isn't anything that they won't fix, so long as it's being addressed under the correct pretenses.
However, you can also be relegated to their quasi blacklist, if you go overboard, with them.
But, their online experience has always been relatively straightforward. The one downside is the expiring report numbers, for online access. That's unhelpful. Consumers shouldn't have to feel like they are hacking into backdoors in order to get access to their reports. But, at least you don't get banned as easily as you do with Trans Union, utilizing these backdoors.
As far as anyone's individual experience; it will inherently vary from one to the next, creating biases that we keep... at least until they start cooperating with us again.
But, I've tried to take my biases out of the equation, insofar as possible, in this analysis... when looking at long term dealings with each major credit bureau.
