Yeah, 5% now, which can allow for larger withdrawals.
There is no limit whatsoever on Roth conversions. You can make those as big as you want.
The downside is you have to wait 4 years and a day before you can use the Roth conversion for regular spending without penalty.
If you don't have the funds to get you to the point where the first Roth conversion has seasoned (from taxable account, Roth contributions, cash), then the SEPP wins by default. No choice, you need money.
If you do, then Roth conversions will be more flexible AND you get some additional benefit from the conversion growth being tax free.
re: flexibility
Once you establish an SEPP, you have to make those annual withdrawals for 5 years or until you reach age 59.5, whichever is LONGER.
If you are age 54.5 maybe that is fine. You can predict with some confidence what your other income will look like for a short time like 5 years.
If you are age 34.5, 25 years is a long time to commit to annual taxable withdrawals. Will you want to get another job after awhile? Will a hobby start making income? Will you inherit an IRA with their mandatory distributions?
In short - age is a factor, access to other funds is a factor, Roth conversion will generally be most flexible.