No need to feel sorry mate, all opinions are valid
Personally I quested my way through Northrend as a holy paly, back in Cata.
Exorcism was cheap as crisps and hurt a lot, and I could pull unbelievable amounts of mobs without ever dieing. Great times!
However denounce doesn't hit for nearly as much, and more importantly it will drain your mana quite quickly.
That being said; if you want to lvl as holy, do it! But realize that it will be a lot slower than going ret