Nikon and Canon are both good choices. Canon does better with the white balance I've always found if you are going to take pictures of your corals glowing under solid blue LED's ever. If that's not a concern then I would go with Nikon over Canon just because of their reputation for glass. Canon is usually more feature based than Nikon, but Nikon focuses on their quality just a trad more. Canon does have great quality still and I ultimately use Canon for my aquarium. If you go for the Canon rebel series like their new T7, get the "i" as this will have the articulating view finder and a few extra features. Meaning "T7i" instead of just T7. Grab a tripod and a macro lens and you'll be good to go. Here is a pic I took of some fruit loops under all blue with my Canon T3i a few years ago. I could never replicate this with my Nikon D7200.