Which is better nucleophile

i know tat Methyl Lithium is SUPER base
Not all nucleophiles are strong enough to act as bases and not all bases make good nucleophiles.

li has jus 1 e- so it can donate easily
but here grignard forms substitution most probably
and methyl lithium not

si my gues is >>>>>>>>>>better nucleophile : Methyl Lithium
corect me if m rong
>>>>>>>>>>

I agree with Abhishek , why does everybody write CORRECT ME IF I'M WRONG?

coming to your Q , weaker baese make better nucleophiles.
both are equally good , except that METHYL LITHIUM IS costly , and thus Grignard reagent is more commonly used.
for yield both are very similsr doesn't make much of a difference