What camera should I upgrade to after owning the canon xsi?

I bought the xsi when I was in grade 8, which was four years ago. I'm now looking to buy a nikon because I personally like them much more, my grandfather gave me his F-801s film camera and an AF Micro Nikkor 60mm 2.8 D and I have used his D500 many times. He also has several lenses so I could borrow them whenever. I love doing macro and landscapes, people pictures don't interest me too much. I want to start doing more star trails and long exposures, I will also be doing a semester abroad in either New Zealand or Australia in university. I was looking at the D7100 or D5200, I would love to get a full frame camera but I definitely do not have the money for that considering I'm going to university next year. I would be getting the body only, as I want to get a 50mm prime lens instead of the kit lens. Which camera out of these two and why, or a different Nikon? And what lenses would be best to look into? My grandfather already has the AF-S 18-300mm 3.5-5.6G, AF Micro 105mm 2.8 and a 24mm 2.8 D. Thanks in advance! (and I have about $1400 to spend but nothing more than that for now)

Added (1). I also will be shooting RAW and want to be able to print large pictures to hang up.

Keep borrowing your grandpa's camera and lenses until he gives all of them to you.

Smile!

You can get a secondhand Nikon dSLR. Any will do. Bear in mind that it will be camera condition first before model and specs. Test the camera thoroughly before paying. That means no buying online.

For lenses, you'll need a macro (which your grandpa already have) and a wide angle lens (which is included in the 18-300mm your granpa already have). If you want more wide angle for more dramatic landscapes, get wider, lesser than 18mm. The 50mm won't be that useful for landscapes. Too narrow.

Spend as little as you can and keep most of your money for college. If you are willing to work at 6MP then the D50 is your absolute minimum to make sure any AF Nikon lens will actually AF. I bought one for my youngest son when he was 9.It cost me around $250 then.

Since you own so many Nikkor lenses, look at the Nikon D7100.It will use all your lenses.