You're wrong. You cannot say 3s is more balanced then 2s because it isn’t. Your advice to this person who asked a question about what to gem is to not follow others advice? Well that makes perfect sense to me.
I’m gonna try again then.
Check out high rated priests, visit [url]http://forum.hydramist.net/index.php?sid=2731b7b5c6ad1026a926802cb992a05c[/url for example. It will answer a lot of questions and give GOOD suggestions about which offset pieces to take, gems and tactics.
Your question was about which gem to take. If you feel your mana pool is too small try to avoid gemming for it (preferably) and think about why you experience your mana pool being too small. Do you find enough oppertunities to drink? Are you using your shadowfiend wisely? or do you just manage your mana very poorly. I stand by sp/haste.