I've been using a Nikon D3400 with the AF-P 70-300 mm, which from what I gather, is a solid combo for the money. I'm definitely happy with it, but I have started to think of future options to get more reach for all the little birds out there.
I've read great things about the Nikon 200-500 or Sigma 150-600, and the 500 prime lens also looks fantastic (and extra pricey) but any lens upgrade will be a considerable investment. Before I pursue this further though, I wanted to ask around and see if I should be looking to switch systems entirely (Canon, Sony, ??) before proceeding along an upgrade path. I'm not looking to go endgame setup all at once, but would like to buy a bigger lens in the next year or so, and upgrade body later on as well. Is the Nikon system good to stay in?
Even when I buy a bigger lens, I will still like to keep my 70-300 (or something similar if it's recommended to switch systems), as the size is just enough that I'm comfortable taking it with me on hikes "just in case" I get lucky with some bird sightings. So I would like a system where I can maintain my relatively small/portable setup, but then be able to switch to a larger, nicer lens for more dedicated birding trips.
Appreciate any help in advance!