The existing 20" tires available for the i3 are summer rubber compound/tread design. IMHO, in Santa Fe, you were somewhat lucky you found them adequate.
The 19" OEM tires are rated all-season. Nobody, to my knowledge, makes a 20" winter tire or all-season tire to fit the i3. There are three winter tires available for the i3, but only two of them are available in the USA: the OEM Bridgestone, and the Nokian R2. Between those two, I believe the R2 is a better winter tire, but I have the Bridgestone. If I have the car long enough to need replacements, I'll go with the Nokian, as I've always had good performance from them in the past. I bought the winter tire/wheel package from the dealer as part of my initial vehicle purchase, and got a deal on them. Now that I have the wheels, the next time, I have more choices. If you read some of the tire reviews on the R2, the general consensus is that it transformed the car when driving in the winter. That extra bit of safety makes it worth the cost to me for swapping things twice a year. The stability and stopping/cornering performance in the cold, nasty weather, is substantial.
As a general rule, a higher profile tire will ride better. Now, the 'look' and performance of the 20" wheels/tires on the i3 is personal preference...the difference in performance is IMHO, minor, and not worth the ride difference.