I've mad a thread or two about these items before. I'd put it like this:
Ancient Golem - Hands down the best of the three. Stats are a bit similar to a Sunfire Cape, but slightly less armor, slightly more health, the jungling benefits, AND, the best part, the tenacity that comes with it.
Elder Lizard - Not as bad as the Spectral Wraith, but it isn't exactly good. In most cases, I find it hard to realistically want this over a Wriggle's Lantern even if you are a jungling AD caster. The proc and ward active a very hard to give up. Also, a Wriggle's is 800 gold cheaper.
Spectral Wraith - Worst one hands down. Its stats, especially for 2400 gold, are very small. I've said this before, but apparently some people don't get it, but after your initial clear on an AP jungler, you will be almost guaranteed to not need this items "jungling damage" to help you clear. Consider that jungle creeps usually have very little MR, if none at all. Why then would you even consider wasting your money on the Spectral Wraith when you could simply build MORE AP for a much cheaper cost, which would amplify your damage to the almost MR-less jungle much more, AS WELL as to champions. Worried about spellvamp? You really shouldn't be, but consider saving 100 more gold and buying a Will of the Ancient in that case, perhaps. Similar, but much better all around stats (minus the cdr which is easy to get from the other good AP items) AND it benefits your team.