We have stayed at both... in a deluxe CL room in December of 2018, and at GF RPC (the deluxe honeymoon/king bed room with either the jacuzzi or soaking tub) in December 2004 and 2019. I haven't done a review yet or posted photos from our 2019 stay, but if you search my posts on this thread and the WL thread you can see photos of our 2018 deluxe CL room and my thoughts on it.
I'm not sure which room(s) you were interested in at GF RPC, but I will say that although we preferred the food offerings at RPC to those at WL (which were still really good, but there just weren't as many items), we really enjoyed having the extra space that the deluxe CL room at WL afforded. I know a lot of people feel that the WL decor is tired and dated, but TBH we really liked it. Call us old fashioned, but my family actually prefers the old school heavy Disney theming...and if you look at my WL photos, you'll see what I mean. Maybe we got lucky, but our room was in perfect shape...and I'm super picky! Now our BC 1BR suite this past December which was supposedly refurbished a lot more recently than WL...don't get me started...

Anyway, the deluxe CL rooms at WL function more as 1BR suites, as they have sitting area/living room with the pull out sofa bed. The only downside for us (and it may be a positive for you depending on how many kids you have) is that the bedroom has two queen beds instead of one king. Our one and only child is now 18, and since she's been a teenager we have found it's a more pleasant, relaxing, and peaceful stay if we each have our own sleeping area, but YMMV. The WL deluxe CL room, because it offers the separate sleeping area, is one of the best values on Disney property (quite a bit lower price point than any other 1BR suite...not counting DVC 1 BR of course), and as such, they are often difficult to come by...so if you're seriously interested in one and it's actually available, I would urge you to book it NOW and cancel later if you change your mind, because we fell in love with that room category for family trips and yet every time we've tried to book it since that stay it's been sold out.
You mentioned that you pretty much already know all the facts about the two properties and mainly wanted opinions...that one's hard, because preference is such a personal thing. IMHO there are things that are truly wonderful and magical about both resorts. We find the CMs to be welcoming and kind at both RPC and the Old Faithful club, and we love the lounge area at both as well. I will say it was an extraordinarily wonderful experience to be staying in RPC at Christmastime with the lobby all decked out and the smell of gingerbread in the air! Once they get that walkway from GF to MK completed the scale will be tipped heavily towards GF because we prefer walking to the parks to having to take transportation, but until then we will likely go with which resort we can find a better deal at if we're looking to book a MK resort, as we are frequent split stayers and prefer to stay at an EP resort for days we're visting EP and HS.
Hope that helps at least a little!