Anyway, I've found this Pony Personality Test. It gives you two kinds of results: a chart... uh... you know the kind, where the mane six are at ends of lines radiating from the center, and the more like each pony you are, the farther away from the center each point is, and it makes a six-sided shape. There's even an indication of how close to the average you are.
This first chart is how I do things in offline life. As seen above, I skew heavily toward Fluttershy, and seem to have given no answers that indicate that I'm anything like Rarity. I'm about half of average like RD, almost average like PP, more than average like TS, and even more than average like AJ.
And here's my results when I answer more like I am online. My Fluttershyness, Pinkie Pieness, and Applejackness didn't seem to change, but I'm a touch more like Rarity, significantly more like TS, and noticeably less like RD than in the last set.
Either way, Fluttershy, so I got this for my banner image:
And this for my full personality description:
Chronically weak and timid, but with a heart of solid gold, you tend to require and depend on the help of your friends in most situations. You enjoy their company, but also enjoy solitude and time away from your friends where you can enjoy the sounds of nature. Just because you know you're weak doesn't mean it holds you back, because you know you're strong where it counts, with your overabundance of kindness, caring, and compassion.
You're often worried about saying or doing the wrong things and also fear rejection. Speaking of fear, you've got a lot of it, often times letting your fear hold you back from doing even the most simple of things, such as jumping across a cliff. But in that fear, you can often find just enough bravery to stand up for doing the right thing if your friends need you.
You may be naive and innocent, and you're very shy and quiet, but you're also a very good listener and are likely the one your friends blab on about their problems to — and while you may feel powerless to help at times, just listening and cheering them on means the world to them. Yay!
(You may gain some amusement from what happens if you choose Scootaloo for one of the answers. I have no idea if other answers yield anything similar, but if anypony wants to experiment, or just runs across something in the course of answering honestly, hey...)
Also, I'd like to suggest something if it's not too much trouble: if you get the same banner as someone else, try to resist the urge to post that picture unless it's a revised version. Otherwise, we already know what it looks like, and don't need to be loading the exact same thing from several sources. The charts are probably going to be unique, so that's fine.