Wolf, thanks for your detailed and honest account! I was in a place where my budgie had just passed away after 12 years and after a year of grieving I thought I might like a different type of parrot for a change, since I had learned so much. I almost got a

from a rescue but I couldn't bear the thought of restricting my birds' flight time to half the time and/or different rooms to prevent aggression. So when a friend said she found a cockatiel I thought it would be a perfect balance. I slowly introduced them and eventually learned that they liked each other and that unlike many budgies, mine is surprisingly not pushy. Sometimes he will try to join the tiel at the food bowl (which makes the tiel leave) or play with him, but he backs off once the tiel says he doesn't want that interaction. Also there are multiple sources of food and places to hang out so they sometimes just spend time apart. Other times they hang close and the tiel puts his head down for the budgie to groom it!
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Pajarita, I did edit out the "no judgements"

The reason I put that in to begin with was just because my crisis is not external (birds attacking each other, sick, feather plucking, bored, etc) as an internal crisis (what is the right direction to go from here?).
I think the fact that I try so hard to provide so much for my birds makes me more concerned that another home won't live up to mine, but you make a good point that I can just wait until I find one. I have a list of requirements (hopefully not too ideal...) and rather than post them I was going to just have people explain what their care routine would be. If they are close I would give them some pointers (such as in diet and entertainment).
You've resolved some of my "crisis" because before yesterday I was thinking, "Am I really going to get rid of a bird?" Since I could see pros and cons to each possibility, I interpreted myself as selfish either way. What I really am thinking is, "Now that I know the idea home for this bird, let me see if anyone comes closer to it than I do." If not, I'm happy for him to stay. If so, I will be sad to see him go but happy that I made sure he's experiencing life to the fullest.
As far as "problems"-- you also missed my huge list of pros/cons and behaviors of each bird! After Wolf's post I cut it down (it was waaay too long, probably like this reply). I did get an air filter do help (a little) with dust and I have a shower perch for him. I only have minor bird allergies so it is only a problem when it combines with other minor seasonal allergies to become major allergies. I deal... The mess I just continuously try to follow up on, which is stressful because I'm so busy right now getting a second master's degree and working. It would help if he stayed in his cage/designated areas better but I'm still working on that. As for volume... it would help if I didn't have a minimalist house! (We have to put our bed away during the day, so it is just a small echo chamber in our room). Also I'm not as concerned for the moment as for when I have little babies that I need to sleep. When we babysit his normal contact calls hurt the child's ears (and mine). I'm open to tips.
I've implemented:
-full spectrum lighting
-stimulating walks
-revised diets (including fresh food, sprouts, etc)
-lots of flight time
-foraging centers in both rooms
-large cages with diverse toys
-bathing opportunities
-keeping a strict sleep schedule
-not responding to screams (using wolf whistle for contact call)
-clicker training activities