The nice thing about fabric pots is you can drag them around and not worry about any hard corners digging in and tipping them over, I put multiple trees on a piece of tarp and can drag maybe 40 gallons total short distances without breaking too much of a sweat. I use the trunks as handles (once they are established and can hold their own roots) when picking up or dragging individual trees since the fabric pots won’t fall off, the handles on root pouches are not strong enough anyway. I stop at 25 gallons since I need to load all of my containers into a truck and can barely pick them up that high if they are wet.
You can keep a tree happy in smaller containers though, if you are going to keep it inside over winter I’d just think about how much room you want it to take up. I’ve never kept a bigger tree growing over winter but sometimes little guys and they usually don’t grow because they are right next to the cold windows, if they did grow though they would need some supplemental light or they would get leggy.
