Hey dayzedandconfused.
Welcome to our Mattress Forum 
A few things stand out right away from what you shared.
First, your sleep positions and preferences are actually pretty compatible. Both of you are mostly side sleepers with some back sleeping mixed in, and you like things on the firmer side but not hard. That usually points toward a mattress with a solid, durable support core and just enough pressure relief on top so shoulders and hips aren’t taking all the load. Since your partner sleeps hot, airflow and avoiding thick, slow-response foams will matter too.
Second, your budget and the fact that this is a “temporary” full-size before moving to a queen is important. It makes sense to focus on good value and durability rather than chasing a perfect, forever mattress right now.
On the models you’re looking at, you’re actually circling some solid options.
Brooklyn Bedding hybrids tend to be good value for the money and fairly balanced, but they can vary a lot by model. I’d want to make sure you’re looking at one that doesn’t rely too heavily on lower-density foams in the comfort layers, since that’s often where soreness and early wear show up.
DLX’s double-sided approach is interesting because flippable designs can extend comfort life, especially at your budget. That’s a real plus if you’re trying to avoid another mattress breaking down quickly.
Arizona Premium and Sleep EZ hybrids lean more into component-style construction. That can be a good fit if you like the idea of being able to adjust or replace comfort layers later, but it also means you’ll want to be thoughtful about firmness choices up front so you’re not guessing.
If I were helping narrow this down, I’d focus less on brand names and more on a few practical checkpoints:
– A pocketed coil support core rather than all foam, for longevity and temperature control
– Comfort layers that aren’t overly thick or overly plush, since you prefer firmer and also sit and read on the bed
– A return or exchange option, especially since you’re coming from something very old and your reference point may shift once you’ve slept on a new mattress for a few weeks
One thing that can really help reduce decision paralysis is picking one “known quantity” and one “adjustable safety net.” For example, choosing a straightforward hybrid that feels right in firmness now, or choosing a design where you have some flexibility to tweak comfort later if side sleeping feels a bit too firm.
Also, don’t underestimate the foundation. If your slats are widely spaced or flexing unevenly, even a good mattress can feel off. When you upgrade the mattress, tightening up the support underneath can make a noticeable difference.
NikkiTMU