Ally is running a promotion right now for new funds deposited with them (good for both existing and new clients). Up to $500 max bonus ($50K new funds), you get 1% of the funds deposited in addition to the 2.25% Ally's savings accounts pay currently. Have to keep funds in there until 1/15/22. This is an annualized 6.25% (at minimum, since Ally increases their rates according to the market) on the deposit amount. Check out the DoC blog post
HERE. Offer expires 10/21/22.
T bills/notes could be attractive if you have high state and local income taxes since the interest earned is not taxed for state/local taxes. You'll pay federal taxes though.
I bonds are 9.62% through the end of October, then the rate will reset to ~6.47% in November. This does tie up your money at least for 12 months though, but if held at least 15 months - if purchased by end of October - you'd get an annualized 8.21% return.* Interest is taxed only at the federal level. You pay a 3 month interest penalty if redeemed before 5 years, hence the 15 months in the calculations.
* from this article
https://seekingalpha.com/article/4546408-i-bonds-what-next