It really depends on what you like. Both you and your dad are right, it just depends on what you like and other dimensions of the ski. If there's rocker you'll want a bit longer of a ski. I would say go with one about your height (175ish, I'm 5'10" as well) without camber for your do everything ski. I have 171 t halls that are really fun, I can't tell if they are a tad on the short side but I am 130lbs. Im currently touring on 182 Praxis GPOs. They are a monster to control but definitely worth the fight. The radius is also pretty big compared to the T Halls so when that edge locks in...I'm in for the long run. Scary thing to find out dropping in on a near 45 degree slope that turned out to have slid recently without any fresh snow on top.
I would say 171-175 for a fun park ski but that's just me. Anything else I would aim closer to 180 but again, there's no wrong answer.
Don't forget to not stress over this, gotta keep it fun.