I have a "Sturdy Safe" RSC that I like but it's nothing compared to a UL rated TL-15 or TL-30 safe.
My advice:
1) Buy a bigger safe than you think you'll need because they fill up fast.
2) If you're looking at RSCs, find the one with the thickest gage steel you can.
3) Anything lighter than a few thousand pounds needs to be bolted down.
4) IMHO unless you're dealing with a real pro there's little difference between TL-30 and TL-15.
5) For a fire safe avoid the cheep drywall filler.
6) Hire movers and someone to bolt the safe down for you. It's not worth being injured or killed to save a few bucks.
7) Get the best safe you can afford. Look for value vs. price.
8) Remember to dehumidify the safe even if you live in a dry climate.
9) If you have a lot of AR/AK rifles or long guns with optics you should be sure the interior is set up to handle this type of weapon.
10) Insurance is better than almost any safe.
Finally, think of security in layers of progressive difficulty. Reenforced doors, alarms, video cameras, exterior lights, etc. all stand between your safe and thieves. Time + attention = their enemy/your friend. More importantly these things stand between the bad guy(s) and your family.
Good luck and please let us know what you decide on.
P.S. For what it's worth, my next safe will be an AMSEC with a TL15 or TL30 rating.