Believe me I have been using power inverter since the time when very few people knew this is also something for backup. When people would see my house lights glowing during loadshedding they will ask "aap generator use kar rahe hain?"
I have used all kinds of batteries during past 11 years. All batteries from renowned manufacturers were of excellent quality a decade ago but then due to the excessive rise of demand, companies not only reduced quality but also tripled the prices. The very first Osaka 130 amperes battery that I bought in 2006 summer costed me 2500 rupees. Now same battery will cost you over 9000 and quality is pathetic.
AGS is a little bit better than OSAKA, Exide etc but their quality is not up to the mark anymore. Before buying Phoenix, I was using 4 AGS batteries and they hardly lasted 1-1.5 years and died. I always use distilled water to top up batteries.
Last year someone recommended me to try Phoenix batteries and believe me now it's over 1 year and they are still going strong. Inverter cuts off charging on time and I get same backup as I used to get a year ago.
Note that in addition to battery quality, inverter quality also matters. During my 11 years experience I have observed that desi and ghattiya quality Homage inverters damage batteries a lot earlier than expected. Homage inverters also give pathetic modified sine wave current and energy savers and fan capacitors will randomly get burnt.
Try CyberPower inverters. They are excellent. CyberPower is a renowned brand. Using their inverters for past 6 or 7 years and not even once they built any fault. While my other Homage inverters are lying around faulty. (CyberPower do not give me a dime for writing this. It's based on my own and several other people experience)