I tried out a G43X, P365X and Shield Plus at the range a few months ago, so my experience is limited with the G43X and Shield Plus, but I'll tell you my take.
There was nothing about the G43X that impressed me. Other than the shorter barrel, it felt like the Glock 19's skinny brother. The capacity sucks for the size, though I'll concede that this point is largely moot since the Shield Arms S15 came out and will be even more moot when PSA comes out with their mag. The trigger felt okay to me. Some people are fine with stock Glock ergonomics, but I can't stand the ergonomics. That being said, it's a Glock: it's simple and reliable. Some people just long for more.
The S&W Shield Plus, on the other hand, was very impressive. The grip was hearty and helped provide good ergonomics. Pointed well when I brought the gun up and I got a good sight picture pretty quickly. It made a strong impression. The trigger was great for me. The gun overall lent itself well to getting precise but fast hits. The only drawback for me was that it doesn't have a rail.
Me personally, I run a P365X with the Magguts 14+1 kit and it's a phenomenal carry gun. If S&W just made the Shield Plus with a rail, I might have picked that instead, because I like having a light on my carry gun.