We need to file our taxes for the first time. Is it better to be taxed as and S-Corp or Multi-member LLC? Advantages/disadvantages?
A Multi-Member LLC is automatically taxed as a partnership unless you choose (or have choosen) to file as a Corporation. Then it is a C-Corp unless you make the S-Corp election. Sadly the 2021 return are now considered LATE even if it went on extension and the penalties are piling up at the rate of $200 per partner/member per month since March. So I would highly recommend you seek local professional assistance with this matter to make this decision since you did not do so before you imparted on this venture.
other problems you could face is that with S-Corp active members must take a reasonable salary. Failure can result in significant penalties. Probably the only exception would be if the activity was rental real estate. but then if such and there were losses, they may not be deductible because of lack of basis. with an unincorporated LLC Non-Recourse Financing (Mortgages) count towards basis but not in an S-Corp. as an unincorporated LLC, other than rental real estate, the earnings would be subject to self-employment taxes. further, an LLC might be better for certain members while an S-Ccorp would be better for other members. you really need to consult a tax pro that can go over each member's individual situation to give you the pros and cons of each.
"Is it better to...?"
That is an extremely complicated question and you need professional advice on the pluses and minuses of forming a corporation. You can also file form 8832 to elect to be taxed as an S-corp without actually forming an S-corp. Either way, you need an expert to go over the election with you.
No matter what, the 8832 election can't be retroactive more than 75 days, so if the LLC was active in 2021, you must file form 1065 for 2021 and you are substantially late (and there are substantial late penalties). If you just formed the LLC in 2022, you would have to file form 1065 by March 15, 2023 (not April 15), and you can't change to an S-corp now unless the LLC was formed less than 75 days ago. If you did make the election, it would probably be best to make it effective January 1 of some year.
An eligible entity files Form 8832 to be treated as a C corporation for federal income tax purposes.
In order to be treated as an S corporation, an eligible entity must file Form 2553. At this point that election would be late and although there is relief for late elections, the circumstances for such relief almost certainly do not apply in this case.