Given your history of WDW properties I would probably say the GCH, esp. given you are staying on points.
I do enjoy the Paradise Pier Hotel. The rooftop pool is sort of neat although its on a lower floor so you don't have magnificient views or anything. It is a nice place to watch the fireworks at night. The slide is pretty much identical to the clown slide at Boardwalk so that is very fun for kids. However, the pool itself is lackluster, it just doesn't have much in the way of personality. And every time I stay there the bar has been closed and there have been no food options. If you enjoy spending time at the pool and enjoy having a quick snack or burger, go with GCH. Whitewater Snacks is one of the best cs options at DL and its right there, they will bring you food and drink or you can get it yourself. The pool also has a nice theme going, a nice slide and some incredible views of the Paradise Pier area of DCA. At night its really lovely. Overall the theming of the GCH is more like what you are used to at WDW. It is very similar to WL, whereas the PP Hotel wasn't built by Disney and is really just a highrise hotel with some fun Disney and Beach touches in the rooms. No grounds, limited food options and more of the feel of a Marriott. I would suggest maybe going over there one day for breakfast, they have a really fun character meal with Lilo and Stitch. I also suggest you check out the
Disneyland Hotel for a meal or just to look around. Its my favorite of the three at Disneyland but since its not available for your dates I can't recommend that one to you! And I have to say, as much as I love the DLH, GCH is really more of a typical, Disney themed, wow factor hotel probably because its the only one at DLR that was designed and built by Disney. And it has some very nice dining options and again, that location is fantastic. You will be in sheer heaven with how easy DLR is compared to WDW as far as park hopping and going back and forth from the parks to your hotel.
Paradise Pier's rooms are nice and oversized and they all come with a couch that makes into a bed. However, GCH rooms are more themed, they have balconies and you get things like turndown service and of course the primo location. I also have found GCH to be even more deluxe in feel than the WDW deluxe's in that the linens and towels are much nicer than the WDW hotels. The rooms are smaller than PP's but the hotel itself is much nicer. And much closer.
The main reason for me to pick the PP is for the savings. Since you are staying on points, GCH would be my hands down pick.