The tripp trapp, after much hesitation & investigation I brought one for my DD who is 11ths. So far, she's managed to push it right over by pushing off the lip under the table, I just managed to catch it before her head hit the floor. This now means I can't pull it up to the table as is the idea as she constantly pushes herself off. New trick is to go completely rigid whilst trying to put her in so it's impossible to get her through the baby bar without injuring her.
I also really miss not having a tray & have ended up using a plastic little chair with a tray on it which she much prefers. The TT is a lovely looking chair but I wonder if it's better for older kids.
(Reading back over this, maybe the problem is my baby & not the chair!!)