I have the LG4.
Pros. Swappable batteries. mini sd card up to 128 gb now. In the future up to 2 tb. Camera is good, I just used auto on the summer fanfest pics. Although from using a iphone camera, I did notice that there is a longer lag on the LG in taking the picture. But the pictures that come out are fantastic. Not as much bloat like on Samsung phones. It has 5.1, and is supposed to get marshmellow. It charges fairly quick. Quickcircle case with qi works fine. I just wish they had a cheap non flip official qi case. But I would recommend getting qi charging for it. Charging the battery seperately seems to take longer than if charging via the phone. Apps work fine. I really don't use much stock apps on the phone.
Cons. Thing I have been noticing recently, and I'm not sure if it's a Tmobile thing, or a android thing. But some apps have issues when wifi and 4g is turned on. Like Simpsons. I can only use it on wifi or 4g, but not when both are on. Battery life will vary. I play lots of games on it, so can lose 20% a game. Usually when I'm out and about, I will need to swap out at least one battery, sometimes 2 batteries in a day. If your phone is searching for a wifi signal, I've seen the battery get sapped quickly. Only comes in 32 gb. The SD is supposed to make up for only coming in one size. And if you do go with the LG, spend the extra and buy a good sd card. Screen can get hard to see. Especially in sunlight. It's not as bright and vibrant as in the Samsung. In standard light, indoors, it looks fine.
IMO, it comes down to how much value you put in swappable batteries and expanded sd cards. If those two are very important features like I place them, then I think the LG4 is the only way to go.