@Xciaphas: To build on what Malisteen is saying about GWM. None of your top spells (with the exception of bless) help its case. Nor that you have options in spellcasting or CD that take away actions from attacking (I mean, even if you neglect fear and wrathful smite and you always look at casting bless, even that takes an action, so you will be starting to attack from round 2). And improved divine smite also plays bad with GWM, cause it's improving the damage you are risking to lose (with that -5 penalty to attacks) for the fixed damage bonus. Not to mention that GWM tends to work best when you are fighting hordes, which is a situation against which the conquest paladin is really well geared (thanks to conquering presence and fear). You have amazing stats, so whatever you decide to do will work, but still, I cannot really suggest GWM. There are better choices. Even if I wanted to go with a greatsword or with a heavy polearm for style, I would still not take it. You really need advantage to make it work (and in a paladin's case I'd say that you need even more -PAM-, since you have enough things already working against it), and I am not sure if your athletics is good enough to justify a PAM-GWM combo (cause if you plan on shoving for keeping your dpr -on which you spent 2 feats already- high, then shoving has much more urgency than it would have for how a conquest paladin would usually use it). But at this point, we are talking about investing in 3 feats, and I don't think the benefit is really worth that investment (for all the reasons I mentioned throughout this post). I am not really saying to grab prodigy and PAM if you are picking GWM, it's more like I am wondering if building to justify a bad choice would be better than restricting the bad choices to just 1 for the build.

Vengeance is much better suited for GWM'ing, so that's another idea if you are really sold on this feat and also want to play a paladin.

In the end, it's your character, and as I said earlier, your stats will support almost anything you want to do. So if you really want to go with GWM, give it a try and see yourself how it works.