Should I stay with an OEM Battery?

I am looking for some feed back, My boyfriend gave me his LG G2X and I am needing a new Battery, I think. The phone is rooted using CyanogenMod 7.2.0 I am not very techie and really not sure if that's relevant to my issue of the phone losing battery life after 2 hours of the phone being off the charger. So I am thinking the battery is shot and I should replace that. I had the same phone at the same time (When we first got it 3-4 years ago) with an extended battery-extended back but I wont use it as the person who owned mine dropped their phone and smashed the screen because of the extra weight on the bottom corners. Should I stick with an OEM Battery or is there anything else I could use that's the same size that seems to preform well? ( I am so sorry if this is the wrong place for my question I happened upon this forum and figured it wouldn't hurt to ask)