To get Mercenary of Sholazar you need to get exalted with one faction and then with the other, which I assume it means you lose the exalted status with the former. I'm interested in knowing what order should I follow. I don't know if it's in my interest to remain exalted with a specific faction of the two.
It's entirely up to you. You can get Wolvar exalted first, get their drink to transform and then get Oracles exalted and continously buy eggs to sell the Proto-drake whelp pet (and maybe have green Proto drop). Wolvar don't have any permanent source of income in their "egg" like Oracles do.
Also, check their Quartermasters for possible tmog items since you'll be giving up those of other faction.