I tried canned coconut cream - it really does whip up the best, but there's a catch. Make sure it's actually coconut cream (the thick layer from the can), not coconut milk, which is liquid. When the can's been sitting in the fridge, that top layer is exactly what you need to whip. I had this one time where I bought it just by the label without looking properly - turned out to be milk, and I couldn't get any foam at all.
Yeah, I totally agree about the fat content. Oat and soy creams are usually thinner, even if it says 20% - they hold their shape worse and can separate. I tried oat cream a few times, and it tastes more watery even when it does whip up. Canned coconut cream is closest to regular cream in consistency, though the flavor's obviously different. The main thing is to chill everything beforehand: the bowl, the mixer, the can itself. Cold helps way more than room temperature.
If you really want to use liquid plant-based creams, add some cornstarch or agar-agar to thicken it - then they'll hold their shape better. But for simple whipping, canned coconut cream is your best bet.