The classes speak for themselves, as amply covered above.
I'll just add that if you do an
Iconic PL (start 15, go to 30), you get that
PLUS a standard class PL - 2 fer one! (If you don't own Iconics, nm.

) Some Iconic PL's are pretty strong boosts, esp if you stack the max of 3.
o
https://ddowiki.com/page/Iconic_Past...ast_Life_Feats
They re-did them a little ways back, MUCH easier than they used to be. Now, just get to 30, take your pick.
o
https://ddowiki.com/page/Epic_Past_L...#Primal_sphere
The Auto-healing and Colors of the Queen (for DPS boost), both from Primal Sphere, are popular places to start, but there are several others that are attractive too (all on that same page).
Racials? 3 of the same race gets you 1 free Racial AP to spend every future life (and a +1 boost to 1 stat), which takes you over the 80 AP limit (assuming your current build has a decent Racial Tree that helps that build).
o
https://ddowiki.com/page/Racial_Past_Life_Feats
In all these, apply the same rule as suggested re
"Which class?" - pick the one(s) that will help your next/future builds the most, just that easy.
Haff fun stomin da cassul!
o/