Just finished watching episode 33 of Blade and once again it's time to seek help from the kind souls of this forums. Before asking, I made sure to make some research trying not to spoil myself while doing so:

My question is related to the Missing Ace movie. I've read that it was shown at cinemas around the time these episodes were released, but it is set 4 years after the end of the battle royale (which I'm in the middle of series-wise) and it showed Blade King form BEFORE the series and it works as an alternate ending for the story.

Now, a pretty good advice to rider movies is to watch them inmediately after the episode that aired the week before the movie came out, but since this is an alternate ending and deals with an aftermath...that kind of confuses me. What's more important, I've read at least five or more people mention that you should watch the movie BEFORE the final episodes of the series cause the tv ending is by far superior and watching the movie afterwards left a bad taste in their mouths.

So that's basically it: without spoilers, what path should I follow?

Blade's movie isn't canon so it doesn't really matter when you watch it.

I think none of the Kamen Rider movies until Decade's are relevant to their series.
They're just alternate universe tales and basically "What If" scenarios.

Den-O's ties into the series. It finishes the second main story arc, and is pretty necessary watching.

There are some arguments for how Ryuki and Kabuto's movies fit in, but apart from Den-O none are canon or even essential viewing.

I watched the movie afterwards and it left no bad taste in my mouth other than I was sometimes complaining about how OOC some parts felt. The movie goes a completely different path with the plot itself (and is more like an AU epilogue) and actually wouldn't really work with the actual plot of the show.
As was said before: It's not canon, so watch it whenever you feel like it.

I don't remember Den-O's first movie.

A lot of people tend to argue about Kabuto's movie and it's possible canonical position.
For Ryuki's...Eh, I guess.

Just finished Den-o and OOO. Going to watch all of den-o and ooo movies soon. I have watched agito,den-o,decade,w,ooo,fourze,wizard,gaim,drive. What kamen rider series do you recommend to me now?

Blade.

Ryuki!