In your opinion which type, model or series is best buy in this moment (as used or refurbished model?)
My goal is spend not so much money, but upgrade it, increasing ram and ssd!
Most of the new MBP's are not upgradeable - soldered Ram and SSD's
The last year you could upgrade an SSD in a MBP were the 2015 models
Also hard to help without knowing screen size prefered and what you might be using the MBP for ? Other options include i7 or i5 processors and if used MBP - retina screen?
I have a Mid 2015 rMBP / 16g mem / i7 processor - 15 inch retina screen with upgraded SSD ( Samsung Pro 512 ) - love it - works great for me - but it is 6 years old
I am sure some others will make suggestions but might be better if you provided a little more info and what your needs are?
All current MBPs are sealed and not upgradeable, the ram and storage are soldered onto the logic board.
What configuration you need will most likely depend on your intended usage? With that said, its probably safe to say the base model of the 16" will easily handle all tasks of the average consumer. If you plan on doing audio/video or other demanding task, then that will obviously impact the configuration
You're looking at a 2012 15" MacBook Pro if you want to accomplish everything you've described. Upgradeable memory and storage, but because of it being the best model that has these options, they are in high demand. A 13" 2012 would be a good choice too since they were produced for far longer in higher quantities making them much cheaper.