I don't believe you can have an FSA and an HSA...
This year, there is a new limited purpose health care FSA that you can have alongside an HSA. The only claims you can make with that FSA are for dental and vision expenses. We're using it this year, and the $281 we just spend on vision exams for a family of 4 at Costco will be our first claim.
In addition to this change, FSAs also now have a limited rollover provision or a grace period (can't have both). I believe the default option is the rollover, where you can carry over up to $500 of unspent dollars to the following year. If your plan elected to have the grace period instead, you would not get the carryover but would have 2.5 months in the following year to make claims against the prior year's contributions.
Probably too late now to make these elections though, open enrollment would have come and gone.
On the original topic, if you have kids and are confident you would be funding college, then the 529 would make sense as the next priority. If not, with FI being the goal, a taxable investment account would be my next choice.
If it helps with the 529 discussion, if you ended up not using it for some reason, it can become another IRA, the only downside would be that the earnings would have a 10% penalty when you withdraw them, on top of being taxed on the income (like you would be with any 401k or traditional IRA). The principal would not have that penalty, only the earnings. Not the end of the world as a worst case. There are also exceptions--if god forbid your child died or became disabled, or much more happily got a scholarship, you could then withdraw the funds not needed for college penalty-free. You can also change the beneficiary--so if your child didn't attend college, you could use it for grandchildren, or for yourself if you wanted to go to grad school, etc.