I currently have 3 Citrus in the original 1 gallon Containers, what would be a good larger size 3, 5 gallon? taller, wider? All are over 1 1/2 foot tall.
I see on older post bigger is better? I worry obout Root Rot, to big of a Container, plus i live in MI. Will be using reccommended 50/50 Cedar Mulch, Peet, little Perlite.

You should try out those fabric containers which are air porous and allows more oxygen exposure to the roots and prunes them to develop a much more dense root ball. I am growing a papaya in a 15 gallon fabric container to avoid root rot and so far the plant is very healthy.The only downside it that soil will dry out more quickly and will require more frequent watering.

For citrus wider is better than taller. Mature citrus trees growing in the ground, 90 percent of their roots are only in the top 20 inches of soil. Citrus roots tends to spread out rather than to grow deep. You could easily and safely go to a 3-gallon, and with caution into a 5-gallon. If it was my tree it would go into a 3 gallon, then in 4-6 months into a 5-gallon. - Millet

Right Millet.

Find you some "Squat Pots" as nursety folks call them