While the i5 certainly is capable for most i5 uses still, and in some areas would marginally outperform the i3, investing in an Ivy Bridge system now (for only a $20 discount), doesn't seem worth it.
The i3 platform at least has the option to upgrade with new parts for quite a while to come yet, and going to a Sky/Kaby Lake i5 or i7 is a much better upgrade path.