I'd say hold out the few short months for a 5S since it's so close to launch if you're set on sticking with iPhone.
I just made the switch to Android after having had my iPhone 3GS for like, forever. I was originally holding out for an upgrade to 5 or 5S, but the emulators made the switch completely worth it Of course, switching platforms is a pain, especially if you've invested into iPhone apps. I have an iPad, so I still have all of the apps I'd paid for, so it wasn't a big deal to me. And yeah, you could jailbreak an iPhone and put emulators on it, but that's just another headache to go through.
I personally recommend to change your platform to android, but if you really want to stay on iOS wait for the iPhone 5S.
Seriously, Apple is going to talk only about how outdated the iPhone 5 is compared to the iPhone 5S on their keynote.
Bought a 5 and I can say other than not being able to jailbreak it currently because of the newer fmw, it's worth the upgrade. I was waiting for the 5S or 5G as well, but realistically a new phone comes out once a year or sooner for Apple really, so why bother waiting, you're just going to see the next one come out and say "But iPhone 6 with iOS 8 is right around the corner and it might have +0.000005% processing speed!", the changes in speed are for the most part quite negligible from 4 to 4S, from 4S to 5 is a little larger, the only reason 4S was worth waiting for was Siri, it doesn't look like 5'X' is going to have anything large like that planned, and once it gets properly implemented, google has a better version of 'Siri'.
You don't have to justify yourself to anyone, unless you want something out of them that they withhold from you for that price. That said, both have a large share of problems individual to each and neither is perfect, but everyone has their reason to pick one, the other, or neither.