Well you hear all sorts of comments that included likes for FF and for smaller sensors. I'll throw one more peanut into the gallery here -
Do you take sports or fast moving action shots?
Do you take shots that are in very low light conditions?
Do you make enlargements bigger than say, 11x14 or 16x20 paper?
Do you prefer physical dials or buttons or happy to dive into menus?
From the above I wont tell you what is your best camera solution but that in your shoes, I would first see what I wanted out of a camera and then start narrowing down.
As an example - DSLR (some models) are ideal for sports and fast motion and mirrorless falls a bit behind though some do compete.
Another example - DSLR doesn't quite have an advantage here anymore as some mirrorless offerings are more than good enough. The gap is closing fast on low light noise handling.
Another example - Assuming your FF is top notch, your lenses and your ability to do post processing, FF would have the advantage on 'uber' large prints. If you print within the above paper sizes, there are both DSLR and mirrorless that would meet your needs as it is a misnomer to say that only FF has excellent optics. Fuji, Zeis/Sony, and others offer some impressive lenses in their catalogue of lenses.
Another example - most digital cameras are for push buttons and menu lovers. Some of us prefer a bit more old school control and that limits the choices in both mirrorless and DSLR, makers like Fuji do pretty good and Nikon's homage tpto the film camera is one solution you might look at.
Last - I was a Nikon guy in film days, and liked also Nikon's DSLR line (still do) but ultimately, for what I like to shoot, the Fuji fit the bill for two reasons - outstanding in camera jpegs along with great RAW files and the handling as well as absolutely excellent optics. There are other makers that have their perks and some lenses that also are outstanding yet not made for FF. My prints rarely go larger than what fits on 11x14 and 16x20 paper and look (according to others) beautiful and amazing.