This is usually a tricky question and really depends on when your visitors visit your site. Some people might say the best time is during the height of traffic.
My advice is to do it before the height of traffic on your site and to be varied. Do not always post at a certain time as it will keep your visitors on their toes and interested. While spacing out your blog posts might annoy some, you might want to actually utilize scheduling your posts, which for those in WordPress, you have that option.
For me, a lot of times around midnight or mid-afternoon, I will post. Sometimes I have a lot to say and will post one article while scheduling the next to publish to my site within the next 8 hours.
However, do not take my advice… watch your site stats and see when your traffic comes in. Aim to post before that spike in traffic so your visitors will have fresh content just about every time they visit. And remember, you do not have to hold off on what you want to say – just say it and schedule it to publish for another time (however, that is usually not a problem, at least from my personal experience.)