I dislike playing tourney games against opponents more than 300 points above/below my own Tournament Entry Rating.
I also prefer to play a variety of opponents, not just those whose TER happens to be within 25 or 50 points of my own, who may be a very small group. Quite apart from the time it takes to fill a tourney in some of the bandings.
I'd like to suggest a bigger bandwidth for banded tourneys, let's say 200 or even 300 points. That should allow a reasonable pool for all groups. Also, top out the lowest group to around 900 or 1000, because there are an awful lot of players at the low end of the scale and it's easy to miss out.
The other things on my want list - the icing on the cake, as it were - would be a variety of time controls and a variety of group sizes. And a consistent regular tourney creation time, that we could all become familiar with.