You might want to take a look at Sony's line of APS-C mirrorless cameras as opposed to the full-frame sensor cameras. I think the price tags are lower on the APS-C ones. Also, if one decides to make the shift later from APS-C to FF, Sony uses the E mount for both types of camera, which can be advantageous. They still do also designate some specifically as "FE" for the full-frame Sony bodies, but there is definitely flexibility overall.
At this point in time, DSLRs are really not the bodies and lenses moving forward. Sure, a lot of people still have and still love their DSLRs and lenses, as there are some outstanding ones, but overall, the camera manufacturers have already pretty much turned their attention away from DSLRs and are developing lines of mirrorless APS-C and FF bodies with native mirrorless lenses to go with them. Starting out new now with camera gear, IMHO the direction in which to go is mirrorless.
Adapters are available as well so that users who still have older gear can use their other lenses on the new mirrorless bodies, too. (An example of this would be Nikon, with its FTZ adapter.) As well, adapters can also be used in some situations to use a lens of a different brand (third party) on a camera body, too. As probably just about everyone here knows, though, I'm a definite proponent of using native lenses and certainly when starting out fresh, that makes sense as the way to go. Also new lenses have benefits that the older ones don't offer, such as better coatings, etc.
Take a look at what is available in general in your overall price range, taking into consideration that you will need to add at least one extra battery and possibly memory cards if the camera body you choose uses a different type than your Panasonic does. You might also prefer to use a camera strap other than the one provided by the manufacturer. Most photographers don't like to go walking around with a strap that loudly proclaims that the camera around their neck is [name the brand]. Aside from that, straps made by other than camera manufacturers themselves often can be more comfortable and convenient in use.
While it might seem tempting to go the small and lightweight m4/3 route, again, like DSLRs, that is a form factor/footprint which seems to be losing fans for whatever reasons. Mirrorless, either APS-C or FF, is pretty clearly the name of the game these days for many manufacturers and their customers.
As for specific brand recommendations, you'll find good cameras by every manufacturer, but each brand has its own special characteristics. One thing to do before buying ANYTHING is to actually hold and handle any camera body and lens combination in which you are interested. See how it feels in the hand. Are the buttons and dials in locations which feel natural to you? Are there too many buttons and dials or not enough? More advanced cameras put a lot out on top and on the rear of their camera bodies, whereas it seems as though many "beginner level" cameras require an awful lot of menu-diving for even the most often-used functions and features. What about other features and functions? Is there something you'd especially want that a given brand or camera body doesn't offer or does offer? Is the presence or absence of that a deal-breaker for you?
Think about the kind of shooting you want and like to do, as that will help you determine what lens(es) you will want right out of the starting gate but also in the future. Check to see that the brand in which you are interested actually offers a good selection of lenses, provides choices in the focal ranges and styles (primes, zooms) which would be what you'd want right now and of course whether they will have the kind of lenses you will want further on down the road in a year or two, when you're ready for them. Lenses which are already available on a camera dealer's shelves are a good bet; hoping that some manufacturer's "road map" of lenses they plan to offer in the (undated) distant future will come to fruition at that time or sooner is a bit of a risk.
Good luck! This is not an easy decision, as many of us here can attest!
