Do the AMD cards generally perform better than the RTX cards? Just wondering if it’s worth adding extra and going for a 3070ti or possibly a 3080
I think you're getting AMD suggestions for two reasons:
1. With their (very recent) driver they have had a performance boost that won't be found in many reviews yet
2. Warzone favours AMD cards and this is the workload you mentioned in your first post
nVidia is also a good choice. Now is the best time in roughly 2 years to buy a graphics card (although I'd argue they are still expensive based on historical president).
One thing I would be aware of for AMD is that Stuttering and lags in Call of Duty: Warzone (Caldera map) are also being investigated right now, in those same latest drivers that improved performance in some workloads. Whilst AMD imply this is related only to the 6900 XT it says 'products such as', so could mean the whole 6000 series stack.