Notes

determining if replacing battery worth it after lets say 2-3 years. Or going for a new phone instead?

Apple - Definitely because replace the battery after 2-3 years because apple phones last very long time and it is more worth it since apple phone has more value. ***

Samsung or other Android - You can go 50/50. The phone value not as high as iOS to want to repair battery immediately but value not as cheap as LG where it does not make much sense to put money into a product that is so valueless. **

LG phone - Definitely just sell the phone because the battery replacement will be a good chunk of the phone's value. *

+* However, phones have completely peaked and are super expensive and only improvements I even care about anymore is probably just camera which gives more incentive to just replacing the battery

+/-* At the 2-3 year point it makes sense but any more and you can get just phone upgrade. and phone upgrade does not need to be newest thing at the time, it can be still year or two old but still newer then the device it is replacing. For example, if you've got a LG v20 that needs a new battery, that will cost you $79. But buying a LG V40, a little over $100 more. For that price, you get all the latest hardware and software. Why not spend a bit more and get a much better device?
You have to factor in age/value of current device and also the age/value of new device you are getting. Just because you do not replace battery and decide to get

-* However, I always get my phones used and depreciated which always greatly makes the price lower for me and better value. This gives much bigger incentive to upgrade if I can sell my current phone. Depreciation and used market biggest discounts from biggest to smallest: LG, Android/Samsung, iOS. With LG discounts it really makes less sense to replace the battery when I can get completely top-end flagship for like 30% of its price if i wait like half a year

TLDR: it all depends on
1. the value and age of your phone if it is worth repairing or just getting new one outright but time to replace battery comes around 2-3 years anyways.
2. And it depends on what the cost to get a new phone compared to how much it costs to replace the battery. the new phone necessarily does not need to be what is currently newest and best out. You can easily get a depreciated and used phone but still upgrade if its newer and higher spec then phone you are currently using.
2a: Price of replacing battery on phone. Compared to:
2b: Price of just simply upgrading instead, compared to price of replacing battery and how big of upgrade the new phone would be.





samsung or apple... yes but lg no since lg i sell would be getting less money and lg i buy also would be going for less and with lg being a tad bit inferior its nice to have a upgrade (Especially camera which is essentially only thing besides battery where phones have not peaked)