I currently own a WE M14 and WE SCAR. I had a KWA M4 before. All three are great rifles, the KWA mags were better compared to the WE ones. Out of 8 WE mags I've owned, 7 had leaking issues lol. At least I got pretty handy with gasket maker

If you're looking for a big ass rifle go for the M14...I've never run into any issues with it, it's an absolute blast to shoot. Functionality wise, the SCAR is my favourite (besides the leaks). Definitely go for the open bolt, aesthetically looks much better and is more reliable.