How important is it that the center speaker fits in that console? That opening looks relatively small and will really limit your options for a good center speaker. With those quality speakers the preference is for a 3 way center with the tweeter above the midrange. A typical MTM center speakers will produce a combing effect that reduces performance off axis. If you listen primarily directly in front of the TV that may be less of a factor but for people sitting on the sides the dialogue will be better with a 3-way.
Here is ShadyJ's review of the RP 800F II. It does have a slightly hot tweeter on axis, but if you aim the speakers straight ahead so that the center seating position is off axis you can tone that down a bit. You could tame it with EQ as well.
The 3 speaker brands you listed are all good options. The Premier 800F offer good value for money and Paradigm makes a good center speaker. The 600C is excellent but large. The 500C is more compact and measures 7 1/8" x 20 1/8" and may fit that console.
Here is Shady's review of the 800F and 500C.
The KEFs could be a good option because their speakers use a dual concentric design so a KEF center will have the dual driver in the middle and offer good off axis performance. I haven't had the chance to hear the Revels but plenty of positive comments from owners.
There is a review for the F36 from 2016 here. If at all possible I highly recommend that you try and find a dealer to demo any of these models. They will all sound different and what appeals to you will be subjective. Otherwise you will need to rely in detailed measurements. The Paradigms and Revels are fairly neutral if you are looking for something less bright than the Klipsch.