If you want a long term phone with excellent features and great battery, then LG G3 is the PERFECT phone.. you can easily get it in between 30-35k with box and etc stuff in great condition..
if pure battery life is your concern and sacrificing a bit on screen resolution doesnt hurt, then lenovo phones with the 4000 mah battery last usually 3 days with dual sim and wifi.. and even more with 1 sim .. unmatched in battery performance.
instead of the A series of samsung, buying a galaxy S5 is a much much superioir choice and can be had in your buget of 40k aproximately. S5 is still one of samsungs better phones to date.
for water proof and shck proof and elegant phone with great battery, Sony Xperia Z2 and ultra or even Z3 can be had in that price.. despite not having as much resale value, they dont need a resale value as they are designed to be worth your money long before you sell it... wonderful build quality and style.
if fan of a largest screen device., the huawei ascend mate and galaxy note 4 can be your great choices with Huawei being a much better phone for all its features and a much larger screen in a metal body. they are a bit expensive above 40k range but THIS huawei phone is a unique and very enjoyable phone.
VIP : all mentioned phones have been used by me, so only giving my OPINION based on my personal experience (So others dont get butt hurt)
Happy buying , who ever is buying, you or your friend, since it isnt clear from your post