whats best in your opinion or is it best to have a choice ??
There's no best. It's what ever floats your boat. I normally take a tarp, especially when hammocking, as a tarp gives a bigger dry area. When I go lightweight I take a poncho, but that's usually in summer when there's little or no wet stuff falling down.
Depends what you want and what you're doing. You can wear a tarp but it's a bit of a faff.
looking forward to trying the Poncho for rain when walking but I think it would be too small to sleep under IMO, I much prefer a lightweight tent