You only have a dual core processor in that system, so you might want to think about at least putting in a SSD, in fact I would say that this is a necessity if you go to High Sierra. I also consider 8 GB RAM to be a minimum these days and the upgrade to 12 GB would not cost you too much, just add in 1 x 8 GB stick.
If you do not want to do these upgrades then I would suggest that you go no higher than Mavericks 10.9.
I hope it helps.