Get both! Used 2014 i3 BEVs are stupid cheap.
All kidding aside, we have had an i3 REx for 2 years on a 3-year lease. It has been an absolute joy to own and drive, even if the stares and questions from random strangers can get a little annoying. We just added a new Bolt to the stable so that we can have an EV for reasonably long trips. The i3 will do it since it's a REx, but interstate speeds aren't great for that little generator and frequent stops to top off the 1.whatever gal tank are cumbersome. Still, for around-town driving, it's hard to beat. It's unlike driving any other car.
The Bolt, on the other hand, is a lot more car-like in its application. It is very hot-hatchy, doesn't buck over road undulations like the i3 can owing to its short wheel base, and doesn't have the rather polarizing exterior appearance of the i3. I happen to like the way they look, especially the "storm trooper" version we have that is white with dark tinted windows, but I will admit, I was *not* a fan of them in 2014 when they debuted. I had a chance to briefly see one in the Amsterdam airport in 2013 as I ran to catch a connecting flight, and at first I was just like "yikes." But a test drive or two later and the looks grew on me.
At this point in time, if I was shopping for a single EV and couldn't wait for or afford the Model 3, the Bolt would absolutely be my choice over the i3. As it is for me, we'll continue to enjoy the quirkiness of the i3 for the next year, then replace it with a Model 3 when we turn it in.