See if you ask me I will definitely pick Z1.
No comparison dude.
Waterproof,Sleek,Light and large battery 3500mAh.
S4 lags heavily and G2 has very bad UI.You will find most of LG phones with MODs.
Special deal for Sony @ 33.7k
Deal of Week 03: Sony India Warranty Xperia Z1 - Water Resistant | eBay
Ok now a piece of advise!If you really want VFM get Nexus 5.Save 5k for your next phone.I know N5 has a bit low battery backup but you can get a nice portable charger!
Among all top tier go for Z1.
Seriously ??? S4 doesn't lag a bit.... If I have 31k, I would opt S4 over N5. Performance isn't everything. S4 has much better battery life & screen than N5. As far as Z1 is concerned, its a big 5" phone (bigger than even Xperia Z, which I feel is a big phone). S4 has same dimensions as my N4, but is a bit longer & is much lighter......
S4 or G2 would be nice upgrade over N4. Seriously, Z1 is a big phone, so better avoid it.
I sport a Nexus 5 myself but dint recommend it as he has already mentioned that battery is his concern. Having said so, I get a backup of 15+ hrs with gaming and voice calls on a daily basis and am happy about it.
I can show you 2 complete days of battery backup from my N4, but screen on time was only 3 hrs with WiFi on, when screen was on.....
As battery life is of main concern, avoid N5. I'm a N4 user. I know what it feels like to be a N4 user & the desire for a phone with better battery life