I'm looking for a new smartphone to replace my Xperia Neo V, can someone suggest a good one?

It's 512Mb RAM and 4.0.3 firmware (Sony stopped upgrading it any further) does not cover my needs anymore, so I need something with at least 3Gb RAM and a decent processor.

LG G3 seems to be a good one, is it recommended or I should avoid it? It has a removable battery which is good but I don't know how much it lasts. I don't find non-removable battery smartphones appealing (even those with Li-Po batteries that last longer). I prefer something with a removable battery so that I can fit it with an extended one from Ebay. A 3000 mAh battery is good for an older generation phone, but this one has a huge screen and I bet it'll suck the battery dry in a jiffy.
The problem with G3 is that extended batteries require a special back cover and that will make it extremely bulky and it won't fit in a case.

Apart for G3 I've also checked HTC One M8 - M9, Xperia Z3 - Z5 and Huawei Honor 6 - 7. Of course they don't have a removable battery, but from what i've seen in reviews they come highly recommended.

Can someone suggest a good phone with a decent sized screen (not too big - something that fits in the hand and pocket)
with at least 3Gb RAM, good processor, card slot and a good battery life?

Note 4. Avoid AT&T if you want to root.
LG V10

Huawei p9 if you wanna wait a while or wait for Note 6 specs.

After going through a number of Samsung and LG phones, I've settled on the Nexus phones. Nexus 6 atm (will wait until end of year to get the new Nexus.

Yes, you give up expandable storage, and removable battery, but for a nearly 2 yr old phone, my battery lasts all day, and with most of my photos and music in the cloud, i only download the music i listen to regularly. Plus there's the benefits of monthly security updates, and prompt updates as Google released them.