Mercenary Stat Comparisons

Similar Stats Across the Board
Mercenaries come in many "flavors"... they vary in class, and by their origin (be it in game or Marketplace, etc). Training mercenaries appears to have no effect whatsoever on a merc's stats, simply opening new equipment slots. Looking at mercenary stats side-by-side suggests that, for the most part, merc stats are very similar across the board (with a few outliers).

Note that a bunch of mercenaries are cut-and-pasted from another. For example, the coercers are pretty much all identical. Furies are often cut-and-pastes of Raffik, etc.

Marketplace Rarity
Regarding Marketplace mercenaries, rarity is not an indicator of quality. Again, using the coercers as an example, it appears that the Rare and Uncommon coercer mercs have worse stats than the Common ones, and no better spells. And Marketplace mercenaries often have worse stats than mercenaries you can get in-game. Caveat Emptor!

Mercenary Spells and Spell Quality
The biggest difference in mercs seems to be in what spells they have, exactly. Most mercenaries come equipped with Master-quality spells, which the game scales to the appropriate level. Some mercenaries have Grandmasters instead. Testing has also shown that some mercenaries gain and/or lose spells at level 110 vs. level 5, and where we have identified these, they are noted.

All mercenaries come with the spell Mercenary's Resolve, and therefore it is not listed in the tables below.

Color Coding
Some of the spells listed are color coded as follows:
 * Healing Spells -- includes some damage spells with a heal component
 * Cures
 * Resurrection Spells

Methodology
To create a good apples-to-apples comparison, testing was done using characters mentored down to level 5, with untrained mercenaries. The characters had all AA, buffs, mounts, familiars, and equipment removed.

Ranger Mercenaries
Note: Some rangers are a hybrid ranger/healer.