There are a bunch of spells that work at in between levels, but in general the following sets for levels work:
All levels: Temperance, Clarity or Boon of the Clear Mind (Maybe Clarity II, but I think that's one of the special ones for the 40ish level+), Harnessing of Spirit, Brells Steadfast Aegis
46+: Virtue, KEI (for 4+ Hr, or Voice of Quellious), Focus of the Seventh, Brell's Stallwart Shield
61+: Was any spell, not sure if there is a new limit on the UF or HoT ones. There wasn't when they first came out. If still not then: Reliance, Voice of Forethought, Talisman of Soul's Unity (or Exigent Focusing), Brell's Tellurian Rampart
Depending on what you have in group, you may go with something different. Particularly going with Rng or Bst Attack buffs vs. Pal Brell's, and doing Druid Skin buffs + Clr/Pal Symbol and Clr/Pal/Shm AC buff for the extra mana regen.
I've thought about making a complete chart sometime, but never have gotten around to it, other than I did find a list of the best HP buffs by spell slot, but it would still need alot of work to include all of the important buffs.
Yther Ore.