Sorry I didn't take the time to read all the responses (shame on me!) so apologies if I'm repeating stuff... but the past 2 summers we visited from Europe and stayed at exactly these 2 resorts
First, relax, you can't go wrong with either option, especially now that the refurbishments are finished at CBR (it was AWESOME, even during the renovations.)
Rooms etc
The rooms and amenities are of very similar standard at both locations. Ditto for the bus service to the parks which is absolutely fantastic on the whole. Only once or twice over a 2 week stay did we have uncomfortably long waits either to or from the resort.
Dining
It's difficult to compare the restaurants because CBR had the temporary buffet while we were there. Ironically, this was one of the highlights of our trip! We were a bit apprehensive because of the renovations, but the replacement buffet was absolutely fantastic. We ate there at every opportunity! I know this isn't relevant for you because the new restaurant is now open, but certainly big bonus points for CBR and how they run things.
In contrast, the Restaurant at Riverside was a big disappointment. We ate there the first night and never went back.
Extras
As I'm sure has been mentioned, the boat to Springs is a big attraction for Riverside. I had stayed at Old Key West a couple of years back and just loved having that boat to Springs, so it was a big factor in picking Riverside for 2017. I don't know, there's just something I love about having boat transport directly from your resort so it remains an attractive factor for me
However, CBR is soon to have the SkyLiner (sorry, I REFUSE to call them gondola's!) station which is going to be awesome too...
Location / Scenery / Theming
I thought (even with the renovations going on) CBR had the edge in terms of scenery and wow factor, you really feel like you are on vacation in the Caribbean, it's stunning. Riverside is themed wonderfully too, for what it is supposed to be, just not as impressive as CBR for me personally.
Conclusion
So overall, I think CBR just shades it if I were to recommend one over the other, but like I said, you wont be disappointed either way.
We're planning July 2020 (can't make it this summer unfortunately) and CBR is on the shortlist
Cheers and good luck!