Well.. there are many in this generation only, but I assume that you want to know about the more popular ones.
THE POPULAR ONES
Pentium G3220 > Pentium G2120 > Pentium G2020 >Pentium G850 > Pentium G640
If you only want to know about the most powerful irrespective of the popularity, then this is the order :
Pentium G3430 > Pentium G3420 > Pentium G3220 > Pentium G2130 > Pentium G2120
Reference reading the model numbers :
Pentium G3xxx --> 4th Generation Haswell CPUs
Pentium G2xxx --> 3rd Generation Ivy Brudge CPUs
Pentium G8xx --> 2nd Generation Sandy Bridge Higher End Pentiums
Pentium G6xx --> 2nd Generation Sandy Bridge Lower End Pentiums
I hope this piece of information helps.