You should give the advent another try, they're pretty neat. On larger maps, their culture superiority really shines, and it makes a big difference. Having a 10%(researchable) bonus over your opponents on all planets, including resource ones, and therefore planet income, turns out to be a big economic advantage. And, as frequently remarked on these forums, the advent have the best mid to end-game fleet synergies

I'm not going to disagree that all things considered, Advent is pretty underpowered. However, when you get their unit combos and if you know how to play them well, they become very strong.

The thing with Advent which is slightly different from the other races is that you really need multiple cap ships to do very well. Start with the radiance and get it to level 6 as quickly as possible. Get the mothership soon after that. If an enemy fleet attacks you, use your radiance to draw enemy fire onto itself. Use Mothership's malice ability, then use the Radiance's Cleansing brilliance on their cap. This usually ends up destroying most ships other than flak and heavy cruisers.

Also, Repair bays are your friend. You have to keep your radiance alive. The whole combo rests on its insane level 6 ability. The next cap ship I like to get is the rapture. Being able to shutdown their caps is very important. Furthermore, using Vengeance and Animosity work very well together. To give you an idea of how powerful this 3 cap combo is, I've killed a pirate base before only using these three caps.

Iconus guardians are also great. They go well especially with this combo and help your radiance not die so quickly. If things start getting out of hand, hit repel, then drive the iconus forward into their fleet and hit repel again. You can use this to have your caps make an easy getaway. Another use for repel is to prevent enemies from jumping out. Sit your guardian near the edge of the grav well. If the enemy fleet tries to run, simply turn on repel and micro your guardian so it's always in their way. They won't be able to escape until they kill the guardian.

One thing to keep in mind - if they have 50 heavy cruisers or some obscene amount of units, make sure you have guardians or your caps will instantly die. Use the cap combo and as soon as it's finished, get the caps out of there with the help of the guardian's repair. All their heavy cruisers should be at about 50% health. Clean up with heavy cruisers/illuminators of your own.

Lastly, When fully upgraded, Crusaders have a crazy high dps (mid 30's). I think it's higher than even enforcers if I remember correctly.

I do not bother with the disciples they die way to fast for me. give me 5 or 5 mother ships and there isn't a pirate fleet out there that can stop them.

The problem with Illuminators is that they are geared towards combatting Support/Heavy Cruiser and even Capital ships. The Advent don't really have anything that is geared towards destroying basic Combat Frigates, and other Long Range Attack Frigates - not until Destra Crusaders.

Well, you have Fighter Strikecraft... but Flak Frigates in SoaSE are imo almost too effective against Fighter Strikecraft. Some abilities used in conjunction with Flak Frigates can 100% negate Strike Craft entirely until they are destroyed. Kortul Devastators jamming strikecraft with an escort of Sentinels, for instance.

That is true, but how often does the enemy attack within 20-30 minutes. Not very often.

Hence their overimbaerdnes.