battery life is also YRMV. it will depend on how you use the phone and also how good your signal is. both the m51 and f62 are mid-range phones. while the s20+ is more of a flagship phone. which will get better battery life? the mid range phones have a much larger battery but with a lesser chip than the s20+. the s20+ has a much smaller battery, but a much faster chip.
as stated by
@Lee Nguyen, it depends how optimized the s20+ is over the other mid-range phones.
it will also depend on how you use the phone. how do you plan to use the phone? for just calling and texting? do you plan on streaming or watching movies? what about games?