Are you asking about seating for La Nouba or Hoop-de-do Review?
For La Nouba, since much of the act is in the air, generally anything about 1/2 way up is recommended.
On our very 1st visit we sat in 204, DD, 9 & 10 - great seats - dead center & half way up. Problem? Well, right in front of us is the lighting/sound control area for the show and I am easily distracted. I found myself gawking at all the lights and buttons on the board instead of the show. And, when the guys move around they sometimes block the view.
Since I am a bit 'stair' challenged in places that do not offer handrails (fear of falling kind of thing) I prefer sitting where it only takes a stair or two to get to my seat. For that reason in the past we sat in the front row of the second level, just off center in category 2 (206, AA, 1, 2, 3 & 4). The only thing I didn't like was that there is a handicap accessable area (104, H, 15, 14, 13, 12, 11) that can block the view partially depending on where wheelchairs are placed, but then I am pretty short so most anything blocks my view!

The same thing applies on the other side (206, AA, 16, 17, 18 & 19)
This year we selected seats at the very top (204, second to last row KK - handicap is in LL, 20 & 21 ). This was suggested by an older CM who has seen the show many times and said he likes to take in everything and having a full view, though far away, suits him well. Also, in this location most of the 'air shows' are nearly at eye-level so there won't be much neck strain which suits me well. Advantage here is that I can enter the auditorium and go down only 2 steps to get to our seats.
As for HDDR, we have been seated on the floor in both cat 1 & 2 and found we actually prefer 2 since I don't like looking 'up' at everything. On our last trip we requested the balcony cat 3 (only one story up and YES they have handrails!). DSIL and I liked the location, but DH and DD said they felt rather 'left-out' since all the action is on the floor. Also, kids would need to sit next to the rail in the balcony for the best view.
So, I guess it depends if you like being in the middle of things

or more of a sit back and take it all in

kind of person!