I've had an older version of the 27" LG 5K and I now have an Apple Studio Display.
The panel might be the same or similar, but the Apple Monitor would still be hands down better overall. It's just put together better. It's lighter, looks better, has better speakers, a somewhat better cam, and takes up less space.
Unfortunately, the deals on the ASD seem to have all expired, but there are refurbs available right now:
Save up to 15% on refurbished Display from Apple Online Store. All products includes a 1-year warranty. Free delivery and returns.
www.apple.com