At this level you have a lot of choices. You unlock the 8th power in your secondary (and will unlock the 9th at 38), but you can also start to take Epic Power Pools (originally for heroes) or Patron Power Pools (originally for villains). It's worth remembering you only have six more power picks total, so you can't plan to take both those secondary powers and all five from an Epic or Patron Pool. You also can't have both an Epic and a Patron Pool, and you only get four pools total (of which you've probably used one on a travel power.
So what are the options?
Don't reject this out of hand. In some pools the last powers are very good (eg the ninth power in a defender's secondary pool is usually a "nuke", a high-damage power that attacks a large number of targets in a radius around the character), or there may be earlier powers you didn't have picks to squeeze in.
Conversely in some pools the final power may not be very good - melee sets are notorious for this. For example, Lord Gorath may never want Unstoppable - it's not completely useless, but the "crash" after three minutes means it may not be worth it as an occasional panic button.
There's good stuff in there - Leadership is good on most support characters, Fighting can be used to further bulk up defences, or a second travel power pool can be used for flexibility (eg, although I Super Jump around, I use Teleport Target to yoink you all over the map and Combat Teleport because I'm too lazy to walk to enemies.
Sorcery, Experimentation, and Force of Will all offer oddball concept powers - eg, the needle I stick into Lord Gorath every two minutes is Experimental Injection.
The Epic Pools aren't "epic" in the sense of being inherently better powers. What they usually do is to allow you to branch out a bit into something your archetype doesn't normally do; each archetype is offered a different selection of Epic Pools, with a different selection of powers. For example, if your archetype doesn't have any defensive toggles, there tends to be a toggle power in all your possible Epic Pools which gives a bit of damage resistance; conversely, if you're a melee fighter, your Epic Pools will offer you some ranged attacks and control powers.
In my view, this is more attractive to "squishies" - more damage resistance is always good, but why take a ranged attack on a tanker when you can just run into melee and smack someone? But Physical Perfection, for example, isn't useless.
The villainous Patron Power Pools are functionally similar in terms of what they offer (shields to squishies, ranged attacks to melee fighters), but there are only four, associated with Lord Recluse's four top lieutenants. They almost always offer a pet summon power to characters other than blasters / masterminds (but unlike mastermind pets, my Fire Imps, etc, they despawn after a time and you can't have them up forever; and you'll have to find room for 3 picks from the pool to get the pet).
As you might gather, the Patron Pools are more thematic, but we'll have to do a short arc to unlock them. On the other hand, if you don't want to go a bit evil and don't have your heart set on a pet summon, the Epic Pools offer a selection of similar mechanics which you're allowed to look over right away.
A dirty secret is that doing any Patron's arc unlocks all four pools.