Without a little more information it's hard to say for sure, but probably not worth it right now.
Is there an employer match to either the 457 or the 401k? That would change the calculus.
If your 401k has available contribution space, and you can afford to contribute more while staying under the limit, and the fees are better, and you're still a long a ways from retirement, then I'd stick with the 401k and maximize your return. The primary advantage of the 457 is the penalty-free early withdrawal option, but you don't need that option right now so I wouldn't pay for it.
If you're going to eventually utilize the 5 year Roth IRA pipeline (by converting one year of expenses from your 401k to a traditional IRA to your Roth IRA, every year starting after the year you retire) then you really only need to have five years of expenses saved up in your 457, to live off while your Roth pipeline conversions "season" for the five years until they can be withdrawn without penalty.
So if you're at least 15 years away from retirement, and you will eventually need to save 5 years in the 457, I'd start contributing to the 457 five years before retirement if you're saving 50% of income, or 10 years before retirement if you're saving 25% of income. If you're saving less than that then you're probably not 15 years away from retirement.
In either case, I'd avoid those 457 fees for at least the next five years.