First, I'm not sure that it's convenient to buy I-Bonds in an IRA. Last I knew, you couldn't simply have TreasuryDirect hold your bonds in an IRA. If you buy through an IRA account with a broker, then TIPS might be a better option.
Since I-Bonds pay CPI + a fixed rate (currently 0.2%) they are guaranteed to beat CPI. Whether they beat inflation depends on your opinion on CPI vs. inflation. There is also some risk that the gov't would default, and some loss in high inflation scenarios due to the trailing calculation.
Regarding CDs and stocks, if I knew the answer I'd be living in a warm climate and trading futures. (I'll note that the average rate on 5 year CDs is currently below 1%. I'll go out on a limb and guess inflation will average more than that over the next 5 years.)
Mostly, you're asking what has been the historic performance. Shiller's data shows some 10 year time periods when stocks didn't keep up with the CPI. But, the worst performance for a 35 year period is about CPI + 5%. So, what's your time frame? And, is that history predictive of the future?
I couldn't find any long history of 5 year CDs. According to FRED, they've paid about as much as 5 year Treasuries since 2000. And FRED has a history for 5 year treasuries since 1954. I compared yields on new 5 year treasuries to the CPI over the following 5 years. I found one long period when they were roughly the same - 1964 to 1979. Other periods generally had the Treasury rate above the CPI. BUT, note that those relationships may have a lot to do with the direction of interest rates and the CPI. It seems that increasing CPI kind of "surprised" investors in the 1970s, and falling CPI "surprised" investors in the 1980s.