1) For what should I be waiting for? An iphone 5s with bigger screen and a revamped ios7?
2) Or an aluminum android device with great battery life and solid construction?
3) I am also really worried that the iphone 4s won't hold its resale value once the iphone 5s is out. The iphone 5 will probably get me more.
1) In the coming months several new Android phones, and a new iPhone will be released. This will provide you with choices that don't exist now.
Traditionally history proves the "S" version of iPhones like 3 to 3S, 4 to 4S, are always better than non S models.
The wildly successful & popular Galaxy S 3 is about to be replaced with the S 4, another phone worth waiting for if you prefer Android.
2) Aluminum was chosen by Apple for style & design continuity with their other products. It dents & scratches easily, since it has no "give" when dropped. That's not a criticism, just a fact. No material is perfect.
Plastic is highly effective & only gets a bad rap here... Because the Android haters choose to act like its the plastics of the 1950's which was far inferior to the plastics of today.
3) I specifically suggested the iPhone 4S as a very good stop gap to get you into a phone now for a mere $99. If you have an upgrade available the minimum you'll pay is $199 for an iPhone 5, whose resale is currently only $60 more than the 4S. An average I get from surveying several sources.
Yet at the end of the day if you don't appreciate the voice of experience from someone who's answering your question and offering a solution, I understand that as well.
Good Luck.