iPhone 5S has always had wifi issues... sick of it

I upgraded from an iPhone 4 to a 5S last year (just before the 6 came out). With the 4, I could always access my WiFi from home but with the 5S, I have always had issues staying connected. I have gotten into the habit of going into WIFI, renewing lease to have my WiFi come back only to eventually drop again. I have an iPad 4, no problems. I have read that people have this problem with the 6.

I've done a lot of research and have reset the network settings, did a soft restore and just now a complete restore. Problem is still there. My router is WPA2... I have a number of wireless devices that have no problem connecting except this darn phone.

Can anyone suggest something I haven't tried yet? I'm really over it....