I am with Verizon, I am outside ALL THE TIME. I guide hunts for a living and am always outside. I have had an iPhone since 2007 or so. My iPhone 4 has been getting worse and worse over the past year and it hardly works now
A few things to consider:
1. Samsung Galaxy S4 uses a display technology called, SAMOLED. It is known to provide bright saturated colors...oversaturation is the norm. The screen colors POP out of the screen! Lots of people like this. Samsung has given some controls over it for you to select how saturated the colors are. Blacks are truly black on the screen. All good so far.
2. SAMOLED is also quite useless outside. For reason beyond my knowledge, SAMOLED washes out under the sun. You can't see what is on the screen in sunlight!!
3. SAMOLED screen brightness is also quite low. As you crank up on brightness of SAMOLED, it drinks battery fast! (Setting at low brightness, it potentially uses less battery than LCD screens.) So, Samsung has limit how bright the screen will go. This is a problem outside under the sun where you want to crank up brightness to read the screen. In addition to washing out, SAMOLED screens are dim everywhere. SAMOLED is great indoors, but useless outside.
4. Since you already own an iPhone, you probably are invested in Apple's ecosystem. You may want to consider that because switching to another OS requires more $$$$ to get the same apps that you have now. (Trust me, i know! I have both OS at home.)
5. With iTunes, you just need to back-up your iPhone 4 on your computer before erasing it. Now, when you get iPhone 5S/C and plug it in for the first time into your computer, then just RESTORE it to your backup. This way, your iPhone 5S/C will have all the stuff that you have on your old 4, including ringtones, contact settings, etc.. That is the REAL beauty of iTunes that no one mentions! You can't do that on Android.
Now, if you REALLY want to try Android, then there are some nice choices out there. Since you're getting it thru contract, then i suggest that you get a top-end unit. My recommendations are:
1. LG G2, which you can order today! Fabulous phone with top internals. The problem is that the Verizon's version is weird. It has wireless charging, which is good, but this makes the phone a tiny bit fatter. In addition, the volume and power buttons on the back are tiny due to this.
2. Motorola Droid...which has good battery life, but average internals (same as Motorola X discussed above).
3. Samsung Galaxy Note 3...same great internals as G2, but a bigger phone! It is big. Coming out soon i think.
4. Quit Verizon. Go pre-paid! If your contract is up or if you're not in a family plan, then go to STRAIGHT TALK...but go with ATT (not verizon). Fabulous value. You won't get LTE, but ATT's HSPA+ (semi-4G) is fast enough. You do have to buy a phone outright at MSRP, but with the monthly savings, you are ahead by 10 months period. No contract. And yeah, you can get any GSM phone you want with Straight Talk.
Hope this helps.