Aside from the Roth piece, not all 401(k)s are created equal - particularly in terms of investment options. IRAs tend to give a ton more flexibility on that front and there isn't really any benefit to having the money in a 401(k) with limited investment options vs an IRA where you can invest in wtfever (excepting if you're planning a conversion).
And you can often get incentives for opening/funding an IRA.
Example: Merrill Edge/Bank of America is
currently offering $600* for moving $200k+ of IRA there (and lower incentives for lower amounts). Normally no fees, and once linked - the IRA assets count toward your BoA
Preferred Rewards customer bonuses. At the $100k+ "Platinum" level, Preferred Rewards status means a
75% bonus on credit card cash back (plus some other generally irrelevant things)
How it works, simple version: The generic "Unlimited" cash back card offers 1.5% cash back on all purchases, no limits. At Platinum customer level, you're getting 2.625% cash back anywhere on all purchases.
If you don't mind playing categories, you can get the "Custom Cash" card with a base 3% back in the category of your choice, which becomes 5.25%. Note that there's a cap of $2,500 spend per quarter for the 3%/5.25% cash back.
*It varies. I've seen $1000 before at ME, but that generally requires already having BoA status. Not always. Or go somewhere else for other incentives.