Cameras, cameras, cameras.
The recent announcement of the new Nikon and Canon mirrorless full frame (ff) cameras brings the dslr v mirrorless debate really to the fore - no longer do Sony have the ff mirrorless market all to themselves - even if they are on their third generation model whilst the other two are just getting going. Some years ago I was almost wooed by the first generation Sony but decided to wait. And I have jumped into mirrorless, but not into full frame but into crop cameras - one APS-C which is about a two-thirds size sensor, where Fujifilm dominate, and also a micro four thirds (MFT) which oddly has a half size sensor ( Olympus and Panasonic ).
So which is best for you? The big advantage of full frame of course is image quality, which in practice means you can crop a much smaller portion of the taken image and enlarge it to say A3 still with good quality. APS-C and MFT cameras will nowadays produce great images at A3 but you have less room to crop without suffering a loss in Image Quality (IQ). IQ is not just about sensor size and amount of cropping though, as lens quality is key. Full frame cameras also tend to be better in low light conditions.
All this ignores however the key driver of moving to mirrorless, which was to reduce weight. But look at the lenses - full frame cameras have much bigger lenses especially if they are fast, and so when you add lens weight into the calculation, the percentage benefit of ff mirrorless versus dslr drops significantly. Also heavy lenses can unbalance a lighter camera. If weight reduction is your aim, then going the APS-C or MFT route will not only get you lighter cameras but also much lighter lenses still of great quality. Which brings us back to the crop question - how important is it to you ?
Anyway, I am not going full frame mirrorless at least for now, and staying with dslr with light weight mirrorless APS-C and MFT with excellent lenses when I want to travel lighter. It is hard not to be drawn by new cameras being released - but they don't often improve your photography unless you specialise say in fast action where autofocus is key and improving all the time. What improves your photography is practice !