What is the best size screen to play chess?

I love chess. Lately, I have been playing more and more chess online. Today I had the opportunity to go ot a OTB tournament and didn't go.  Instead I spent time customizing the way chess.com looks for me.

 I officially now spend more time on chess.com than the time I spend on my email and web browsing combined.

I am using a 24" iMac.  I wonder if this big screen is making my chess.com experience more pleasant than others?

 What screen size do you use?