The i3 is the most powerful, and you will get the best performance. If your budget is a huge concern, then go with the Pentium G2120, as it not too much worse, and much less.
Here is a quote from CPUBoss, a really helpful website:
"The Intel Pentium G2120 and the Intel Core i3 3220: two cores released in the same month, but one being somewhat better than the other.
The biggest difference between these two is the clock speed and the oveclocked clock speed. The i3 outperforms the Pentium by a decent amount there. The i3 sports 3.3GHz per core, while th Pentium only manages 3.1GHz per core; not only that but the cores if the i3 are hyperthreaded, doubling the amount of threads they can handle up to four, which further adds to the fact the i3 is better. Not only that, but the i3 also offers a significantly higher overclock clock speeds than the Pentium. The only downside of the i3 is that it has a lower performance-per-watt score than the Pentium, but that’s easily overlooked when it offers higher speed and more threads.
So, yes, as a conclusion: the Intel Pentium G2120 is the lesser processor in this comparison, with the Intel Core i3 3220 being the superior."
I hope I could help!
Thanks ill go with the G2120, ThanksYou helped!