Medela mini breast pump or Avent?

I've used both, one with each kid. I preferred th Avent one as it was quieter than the medela. Otherwise both worked as effectively as each other.

I did however like the bags for freezing that medela had. They were very useful, and attached straight to the pump.

As for learning to use the bottle. With DS he was really good when he was under 3 months then we stopped for a while and he was hopeless to get started again. DD however took to it from day one no questions asked and easily swaps between BF and bottle. So I guess it depends a lot on the kid.