Is there a "perfect" crib out there, with adjustable height, a slideable side you can open/close?
I don't think so because I believe they banned the dropside due to injuries. here are probably a lot of barriers to invent such a thing, at least in the USA. I got the ikea non dropside and I am too short to put my baby in there. We cosleep so it's okay, but if I was really relying on it I'd be pretty bummed.
Sorry I am no help. Are you handy enough to invent it?
Please invent it! :) I've racked my brain to figure out an easily-removeable "4th side" for the sidecar, for when baby's there alone. I didn't feel comfortable with the safety of too much improvising, so instead DD starts the night in a pack-n-play then comes to the sidecar when I go to bed.
Definitely look for a high-quality, sturdy crib. Our crib is a Ragazzi dropside, bought used before dropsides were banned. It's awesome! Sturdy enough for me to scoot in there to nurse instead of trying to move a sleeping baby back and forth.