Should I upgrade to the Iphone 5S or wait for a new 4 model Iphone?

I really don't like bigger phones.

It's outdated. I also doubt Apple will make a new 4" phone. They kept making the 5S because they usually keep making the previous year model. To sell as the low end model. The only time they varied from this was the iPhone 5c. Which was really just an iPhone 5 with a new case to visibly differentiate it from the 5s.

So the next low end phone will likely be the iPhone 6 and the 6 plus dropped. The high end models will be something like a 6s and 6s Plus or just a 6s Plus.

I have iphone 5S and I think its great, never had 1 issue with it ever. I think Apple has an announcement Sept 9(?), chances are thats going to be multiple things including a new iphone since its been a year. Iphone 5S might drop in price then, but thats still 4 weeks away.