Fun, opportunity, action and interaction 
I think what most are looking for when deciding where to create a new character.
So, basically, "I want my cake and eat it too". I believe you're setting the bar too high. If such a realm exists, there would be an entire subforum singing its praises 24/7.
Often times these criteria work against each other.
A fun realm will have lots of ambitious, competent young nobles. Your noble will have to compete against two or three of them for any position that opens up, assuming that the older, equally ambitious and competent nobles let one of these positions slip out of their hands in the first place. So that will hurt your "opportunity" criteria. On the other hand, realms that hand your noble a lordship just for showing up, are mostly ghost towns. If "having a pulse" qualifies your noble to a lordship, then don't expect the other lords to be capable of much more than breathing.
An action-oriented realm will have a war close to its border. In other words, your noble are going to be fighting against neighbors. Most of the interaction will be negative ones, in other words, insults shouted across the trench lines, assuming that your Marshal doesn't tell you to shut up and show proper decorum to the enemy scum that just torched your region. On the other hand, the realms with the best RP, at least in my experience, are geographically isolated realms that hardly ever fights. They have good RP because it's their only way to attract players, and good writers get promoted and rewarded instead of the good strategists and tacticians.
Yes, I'm no fun.
So think really hard about what you really want. Because you can't have everything, and if you join a realm expecting perfection, you're just setting yourself up for disappointment.
