Worst Bond film ever?

I've always rated A View to a Kill as the worst--this one seems to me better than that although it is one of the weaker efforts. Never Say Never Again has the least appealing score and, despite a really serious challenge by Madonna, the worst song ever in a Bond film.

as an "unofficial" production I don't even count it as a 007 film.

having said that, as a film, it is one of the shitties Bonds.
Moore's 'Octopussy' was superior in 1983.

Quantum of Solace for me. That was barely even a Bond film and I far-and-away prefer Never Say Never Again.

It's an out-of-francise film delayed by years of legal shenanigans and Connery knew he was too old by the time they made it - not sure it's meaningful to rate it with the offical Bond movies.
You could argue it really sits alongside the spoof Casino Royale where David Niven (and possibly several others, been many years since I saw it) played Bond.

spectre, QOS, skyfall

It's one of my favorites. I saw it at the theater along with Octopussy around the same time. This one aged better.

I rather like this one, it's super cheesy and silly, but it's great fun and Connery is at his best.

Personally I think "Moonraker" is the worst, the later Moore films were just unbearable. Moore was pushing sixty and over it all, and the movies were ridiculous, and failed as both comedies and action films. At least "Never" had some laughs.

There are two worse ones. Diamonds are Forever and Die Another Day.

Then there are ones that are basically just as bad as NSNA (if maybe just fractioanlly better) like Octopussy, Moonraker, TWINE, Spectre, and Skyfall.