I never subscribed to the idea that tantillions gave more skill than other mobs. The reason that
i spent months at "Tant Plateau" (rest in peace) is that it was unique in offering a good density of:
- a small (hp) mob
- with small damage
- and high aggro
That tended to lead to fast skillgains because (1) there is a "skill loot" you get each time you kill a mob, and so you get proportionately more skills per damage (so per pec) from smaller mobs,* (2) you could take a lot of hits (increasing chances to gain Evader skills) with relatively little damage, and (3) you could do both quickly because they would "come to you".
I'm not aware of any decent tantillion spawn in game since VU10, but perhaps someone who has been around more since then can tell you differently. I do miss fighting off waves of the little pink bouncing boogers...
You get a similar benefit from small merps for similar reasons, and that may be the best bet. I got pretty good skills from the merp Iron Challenge, and approached it about how i did hunting tants. Sadly, there just isn't a similar spawn of merps. I've had a fantasy of owning a little tiny OLA with a high density, low maturity tantillion spawn, which i would put at 1% tax. Maybe some day.
* i do believe this was tested, but don't recall where. Sorry.