It's true, there is no one-size-fits-all. In my case, for the moment I've opted to max out my tax-sheltered accounts, because the tax savings constitutes (to me) a significant portion of my income that I can then plow into taxable accounts. Right now I'm about 40/60 between taxed and non-taxed in terms of what's where, since my income is going up faster than the limits on taxable accounts I expect that ratio is going to shift to something more even and eventually to a larger share being in taxed accounts.
I have a couple of thoughts on putting money into tax-sheltered but age restricted accounts. First, assuming you're healthy and planning to live to your mid-70's, your post-60 life is likely going to last as long (or maybe longer) than your pre-60 ER life. Second, although we're all superhuman superhealthy wunderbeings who plan on simply dropping peacefully dead of old age at 95, the fact is that as you get older, you are more likely to need help (and the money to pay for it). i.e., you will likely not be as mobile at 85 as you were at 40, and so hiring someone to come in and help you with a few things once or twice a week may become a necessity rather than a luxury. You may develop a medical condition that is expensive to treat. And so on. Also, while I don't think social security is going away completely, I do believe the benefits for people currently in their 30s will be less generous than they are at present, so I have my ER "requirements" excluding any expectation of SS, which does mean needing a larger nest egg for later in life. Finally, it's harder to go out and get a job in your 70s or 80s than it is in your 40s, so you need to have a better set of alternative safety margins than you might in your 40s or 50s, when returning to the traditional workforce is a more feasible "backup" option if your savings start falling short. For these reasons, I think it's not such a bad thing to have a good chunk of money tied up in accounts that can't readily be accessed before age 60.