I used to use Skype, then Zoom for group calls and FaceTime for personal chats.
I still use FaceTime for one particular friend but I tend to mostly use WhatsApp now for both voice calls and video calls to other close friends and family, sometimes switching between the two.
I never videocall anyone unannounced - I would use WhatsApp voice call first (in case they are having a bad hair day or not fully dressed etc!)
We sometimes switch to WhatsApp video call during the call if it’s convenient for us both.
I like the way you can switch between voice and video on the same call - and I get a better signal on WhatsApp via my Wi-Fi than if I’m telephoning using my mobile signal.
I used Zoom a fair bit during the lockdowns. My son still makes video calls on Whatsapp quite regularly when he is with the grandkids.
The advantage of Zoom calls was that it was on my desktop computer using my web cam and green screen whereas Whatsapp calls are on my phone, I hate the vertical screen (though it is possibly more practical)