I was using FCP since version 1. When X came out, I gave it a try at the Apple store and just wasn't impressed. Told myself I'd wait it out to see how it'd progress. In that time, I migrated to Premiere. Being a heavy user of After Effects and Cinema 4D, the integration and dynamic links are unparalleled to what FCP X could ever offer in its current form.
That's not accurate. The current form of Final Cut Pro X / Motion is much more powerful than Premiere /After Effects.
Both allow you to create motion graphics in AE or Motion and then bring them into the video editor without rendering. FCP X has always been able to do that with Motion. But there is much more integration than that.
For example, Adobe has Live Text templates so you can edit the animated text from AE right inside Premiere Pro. FCP X / Motion are able to do that, but much more. You can edit the font of the text, the color of the text, the drop shadow, any parameter you want right in FCP X. And you can set up rigging for anything in Motion to edit right in FCP X. Check out "rigging and publishing" in Motion. It's MUCH more powerful than AE. So, for example, if you create an animated lower third in Motion and the color of a rectangle the text is on top of is blue, you can set up your rig to be able to select Blue, Red, Green, Yellow right inside Final Cut Pro X. It's very easy, but powerful.
I used After Effects from 1994 when it was CoSa After Effects till today. Motion's keyframe-less system is superior, IMHO. I can do things much, much faster in Motion than AE, and because it's using dynamic behaviors instead of key frames, it's so much faster to move things around and edit. Motion has full integration with Cinema 4D too.
Motion doesn't require multiple timelines with Pre-comps like AE does. It doesn't require I manually go in and click on stop watch icons to create key frames.
Motion has a Layers palette, just like Photoshop does. This is really awesome. You can group objects easily in this palette and then just select the group and animate it. Want something in one group to go to another group, just drag and drop it like you would in Photoshop. No multiple timelines to dig in to, no pre-comps.
So if I want to animate the moon orbiting the earth and then have the earth go across the screen, this is what I'd do in Motion:
1. Put the earth and moon images on the stage. They are now in my Layer palette.
2. Drag and drop the "Orbit" behavior onto the moon.
3. Select "Earth" from the pop-up parameter in the Orbit behavior to tell Motion what you want the moon to orbit the earth object
5. A circle path automatically appears. If you press the space bar, Motion will animate it all in REAL TIME, looped, and as you drag that circle path in and out, it expands and contracts the orbit the moon is making around the earth. You can also drag the speed parameter, the direction parameter, all in REAL TIME as it animates in a loop on your screen. You are watching the moon orbit the earth with literally 2 clicks of your mouse.
6. Group the moon and earth and now you have a folder in your Layers palette. You want to see them separately? Just like Photoshop, just click on the arrow icon to the left of the folder and it reveals everything inside.
7. Drag and drop the "Throw" behavior onto the group you created. Throw is the behavior that moves objects in a direction at a speed.
8. Again, press the space bar to animate it in real time and click and drag the arrow artwork for the speed and direction of the Throw behavior.
Done. You now have the moon orbiting the earth and both of them moving across the screen without creating a single key frame. The power of not having key frames is I can drag this whole thing and move it where I want without worrying about screwing up key frames, nor do I have to deal with multiple timelines.
There are lots of amazing behaviors including gravity, wind, etc. PLUS, the parameter behaviors are fantastic. For example, if I want to add some random to the speed of the Throw on the whole group, I just drag the Random paramater behavior and select the Throw speed parameter. It has oscillate, etc.
Very powerful stuff. Way beyond AE's ability.
Motion does have traditional key frame capabilities, though, with a very powerful key frame editor palette for changing the bezier curve, etc.
This real time animation capability of Motion blows AE out of the water. There is very little need to render a RAM preview in Motion. Apple was way ahead of Adobe in using the GPUs to accelerate their software, plus Adobe AE still doesn't use hardware acceleration in Mercury with Radeon cards, only nVidia.
In regards to FCP X, I prefer the magnetic timeline paradigm over the traditional tracks. I never accidentally create gaps in my timeline. It's impossible. It's so much faster to edit with this system than traditional tracks. Everything is pinned so when you make one clip shorter, everything past that moves into the exact places it should be.
FCP X has many things since version 10.0 that Premiere has been catching up to. For example, auto syncing your secondary audio with your video clips. It's been in FCP X since day 1. It's fantastic. You do it right in the bin, not in the timeline. Just select the audio clip and video clip for "scene 1 take 2" and right-click and select Syncrhonize and it does it automatically.
The multicam is superior in FCP X too with a lot more angles and you don't have to flatten it at all like you do in Premiere Pro. Doing music videos is a breeze in FCP X. This is another catch-up for Premiere Pro and the performance of the multicam is superior in FCP X without flattening.
The media management in FCP X is also superior IMHO. The key word system is just fantastic coupled with the Timeline Index. It will analyze your video clips and tag them with key words like "One person" " Two person" "Group" "Close Up Shot" "Medium Shot", etc. When I import RED rd3 footage, Premiere creates multiple folders and brings in duplicates. With FCP X, I can just select "Day 1" folder and it will only bring in the video clips in all the sub folders and no duplicates. It tags based on the folder names too.
Then when you add FCP X's "Roles" feature, you have a fantastic way to manage a huge amount of assets. Editing a feature film is a breeze in FCP X.
BTW, the speed of FCP X is fantastic. On the same Mac Pro system, FCP X flies with native RED rd3 footage at 3:1 compression 5K and I play it in real time and scrub in real time with my house cursor with the video at 100% resolution on a 4K monitor. I have CC 2015 and Premiere Pro on the same system requires it to be at 1/4 resolution to be able to play it without rendering.
Everyone should use what they prefer, obviously, but I find most people who bash FCP X just don't know what they are talking about.