Social media problems with photos

Having solved the age old problem of facebook's dimension for getting photos sharp, having uploaded my photo to G+ I noticed that the quality is words I can't really say on this site, but hopefully you've already caught my drift as to what I'm thinking, in short, it's not good

So can anyone tell me what the good dimension is to getting photos to look good on G+ is? I don't want to upload large photos just at least 1000px longside

Since anything up to 2048 on the long side doesn't count against Google's free storage space amount, that's what I use. My results have been acceptable at that size.