Debian 8 Jessie is oldstable and will be out of support in
2 years. Backports for Debian 8 Jessie has already been archived and has an expired certificate, which will cause you issues if you try to add the backports repo (which you'll probably need).
I've been basing new systems on Debian 10 Buster, its very similar to Debian 9 Stretch but with newer packages and a much longer support cycle (compared to the remaining long term support left on prior releases). Debian 10 Buster will officially be released in a week, though its fine to use right now.