Is it better to equip items with (+ stats) or (+ spells)? 

my thought on this is that if you are healing in a group then +healing/dmg is what you want but when soloing stats seem more effective a nice balance between the two never hurts though

IMO, the answer is... it depends.

I have lots of different pieces of healing gear that I carry around for different situations.  For long fights, I use a regen set.  For short fights, or fights where I have plenty of other regen (Shadow Priest and such), I have a max-healing set.  For fights where HPS is most important and usually for trash, I have a Haste set.

The other thing to keep in mind is that you can effectively turn regen into healing or healing into regen but changing the ranks of spells that you use.  If you have lots of regen, up-rank your spells to get more healing through-put.  If you have lots of plus healing, down-rank your spells to get more mana efficiency.

Using that as a baseline, I've computed healing equivalency points for all the stats and I generally wear the gear that has the highest point value, but I still have the other sets for those special situations.

So, the real answer, I guess, is that you need both.