I want to install a sub panel in my shed
The wire will probably run around 150'
And I will have heating and air unit in the wall that needs a 230v line
Plus 6 receptacles that were already installed there on a single line

So I'm wondering what kind of a cable do I run to the sub panel?

First, you need to get the Amperage ratings for both the heating and AC.

Once you have an approximate amperage, you can determine your total load. There will be a voltage drop consideration because of the 150 ft. run of cable.

Also, are you planning on 15 or 20 Amp outlets? I would suggest 20 amp. Pleaseinclude lighting, inside and out.

You should be using GFCI protected outlets.

The unit requires 30 amp circuit and the outlets are going to be 20
Though I just though of it and there is going to be a 1/2 bath and single sink kitchenette (sp?) in there too so I know I need a separate 20 for that plus two regular fans

A KITCHENETTE IN YOUR SHED! This is starting to sound like a cabana house...
Well based on the combination Heat/AC, the counter outlets, lights, and what every good kitchenette needs, a refrigerator, you will need a minimum of a 60A line to your "shed".
As far as what Don mentioned about voltage drop, if you use #6 copper, at 240V, with a 150' run you will get an allowable 5% voltage drop, and there is no need to increase wire size for a 60A, 240V circuit.
If you plan on burying a conduit to this shed I would recamend at least a 1 1/2" PVC conduit, also don't forget your minimum required ground size will be #8.
Let me know how you make out, or if you need any additional help.

Well the kitchenette is an additional option that might/might not be there I just want to future proof it, plus the shed will act as an office

So I can run #6-3 with ground to the sub panel with a 60A breaker and it will be enough?

I also have another question, there is already a sub panel box in another part of a house
It has three 30A breakers in it, they are for a heat and a/c unit, water heater, and a clothes dryer. I believe that the cable that runs from the main box is 10/3 w/o ground (I believe, it might be #8 but I'm not sure I'll check tomorrow) with a 50A breaker on it,
Will that be enough to run all of those things or do I have to go up in wire size?

I checked it out and it is a 10/3 wire, so I guess I have to change it?