Roth IRA

Assuming you are at a lower salary/tax bracket, it could be s good idea to throw the max in a Roth IRA for a few years in a row.

Yeah the 401k is low fee and and has been performing extremely well these past 4 years. Same with my Roth, but I know they both have different tax benefits that would be good to diversify between them.

Tax-advantaged retirement accounts next. Roth IRA. Max it out every year!

If OP is planning on working soon (or already is) I would actually put all of it in HYS and buy into a Roth IRA for the max they can every year for at least two years with the money. It's generally really hard to save money when this young and getting maxed into a Roth IRA this young will pay massively for OP when they retire.

Consider $7.5k of that s&p500 in a Roth IRA and then the other $7.5k in a normal brokerage acct for expenses you may need in the medium-future

Roth IRA is the best account for tax advantage. Put 7 in now and 7 more in April and the rest in a hysa

If so, I would max out a Roth IRA (7k) then put 3-5k into a HYSA, remainder into S&P and potentially also give some to charity if so inclined.

once you've got more of a buffer you may want to put that same cash into a Roth IRA instead of your 401K anyway.

Having some Roth lets you control your taxable income in retirement. If you're retiring early, that might help you stay under the ACA subsidy limit of 400% of the federal poverty level, but it can also factor into things like social security taxes. Roth money also makes for easier inheritance. For my wife and I, paying 12% in taxes today to lock in all the benefits of Roth is well worth it, even if we might have paid slightly less in retirement.