Well, temple of healing is technically better, but it requires Heroic age rather than classcical age, and and investment of 1200 food 500 gold + The cost of the tech (favour pplus gold I can't remember the exact value) to get it, whereas Healing spring only requires the 400 food investment in classical age.
I must say that Healing spring is used more often, Forseti is pretty popular for both Thor and Loki.
You'd probably be better off investing your gold and favour elsewhere in early Heroic, so temple of healing won't get researched until quite late on usually. In this respect, Healing spring is more useful because it is accessable from the classical age.
However, in late game with all techs researched etc, temple of healing is better because you can have multiple healing temples wherever you want on the map.
Sometimes you need to scare the lambs,
tell tales of evil bad wolves.
Because if there is nothing to fear,
they might think for themselves.