How do you go about selecting your character powers?

Concept primarily, although I've done it backwards plenty of times and made up a concept to go with a power I wanted to try.

What's most efficient or powerful is absolutely last on my list of criteria, and I even take sets and powers everyone else tells me "suck" just to check 'em out.

LEGION OF VALOR - Be a part of the Legend!

My criteria:

1. It has to be very capable of soloing at a decent speed, no slower than a corruptor.
2. It has to have buffs, debuffs, or both.
3. I have to like the visuals/animations.
4. I have to have a name I like that fits with the powersets, and it can only be one word.
5. I have to have a costume I like that fits with the powersets and doesn't look too much like my other costumes.

Because these are so stringent I only have 2-3 characters I actually play, all corruptors other than my fortunata.

I usually try to "fill in the holes".

it varies toon to toon.

a lot of the time i figure out if i need a new toon to begin with and what set i want to start with. then i figure out 6 or 7 different builds with various secondaries and decide what works best (balanced, least holes or just has a decicive focus in one direction).
ie: An Empathy/Sonic Defender was a Navy medic assigned to a Marine unit.
Electric/Electric Scrapper/Blaster for End drain.
Illusion/Rad for soloability that i built a law enforcement background around.

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i've deleted alts that i liked initially but found later that the concept or power sets weren't working as well together as i'd hoped.
usually by 20-30 i know if its something that'll stick around.

another BIG thing about power set selection is wether or not i've used it for another charcter. it's rare that i'll use a primary or secondary that i've already used somewhere else.

I go by usability and concept. For example, I had a concept for a Dual Pistols character and made a DP/Traps corrupter, but traps kind of sucks to me so I re-rolled it as a DP/EM blaster that also fit the concept but not as well as the Corr.

So for me concept is very important as long as it doesn't get in the way of fun.

Pretty much all of the time my characters are concept characters. I'll get this cool idea for a character, then decide which power sets fit him best. With power customization, I can make any power set into something else. Water control? Blue empathy! Psychic Melee? Purple/Pinkish martial arts.

There are some times where it's the opposite. I'll pick the two power sets first, then create a concept to fit the parameters. Of course, this doesn't happen often, as it's difficult to create concepts on the fly.

I don't play sets because they're "FotM" or "Uber" sets. I play whatever sets would fit my character and see what happens. =D

P.S. Did anybody else misread the title and think it was somebody asking how to actually pick your powers?

What powerstes do I choose? It really depends on what it is I'm creating. More often than not I have a concept in mind and I will select the powersets that best fit.

As to what I thought the question was when I first read it. Selecting powers within a set, that depends in a small way on concept, basically I'm I going to be dishing it out, or am I going to be helping my teammates more? That will be the difference between weather I take a support power as opposed to an attack.

I pick my power sets bases on concept as well.

First-concept.
Second-"I haven't played that set before."
Third-"man THAT power looked cool, what was it?"

I put a lot of time into making my characters.

First, I generally make a character because I feel inspired to try a certain archetype or powerset. So I head to the board for that archetype and see what powersets looks fun, or check if the powerset that's piqued my curiosity sounds like something I'd really want to play. If it does sound fun, I'll look for a primary/secondary that works well with it and again, sounds fun. (Generally, I want combinations that can solo -1/x8 missions by around level 35, but can still offer something to a team. Oh, and have no endurance issues by then.)

Next, I try to see if I can think of a good concept for it, provided I don't have one in mind already. Concept is as important as performance to me. I'm willing to bend things a bit (my Rad/MM Blaster has a neutron star theme), but something like an Elec/Stone Tanker really wouldn't work for me.

Then I make a cheapo build (Generally under 250mil, something I can make before level 47) for them to see how well I can get them to perform on a budget and to compare them to other powerset combinations I might be thinking of.

Then I have to come up with a name that fits the theme, which is always the hardest part.

If all goes well, I'll have my next character.