Well attacking pets are great when they're fed but with some feeding and good equips and a crit weapon, an attacking pet could be great such as Fred, Victoria, Niss etc. If you just want one that can help seal with you then you can choose a pet like Qlaya who is fast but generally low con or Shasha who has good int and can seal two at a time etc.

If you don't mind having a pet that can't RB yet then you can ffor Eva for her seal or Athena for her nice ark or Venus for her seal etc.

All in all it's up to you to decide but these are some suggestions to help you along the way of making your decision.
Good luck !