I will be having a 60amp sub-panel installed in my attached garage to run various machines. My current thinking is I would like as many spaces(8,10,12) in the panel as possible to allow for possible future expansion.
I have been told Square D is the way to go. I am fine with Square D and like there panels.
Any recommendation on models of panels that have many spaces and can be surface mounted as a sub-panel?:)

Any opinions regarding Square D Homeline Load Centers vs. QO Load Centers?

Any recommendation on models of panels that have many spaces and can be surface mounted as a sub-panel?
Unless the garage is over 2000 sq feet big, be a little bit realistic : how many circuits will you ever have there? A 60 Amp board... One for lights, one for wallsockets, one or two for machinery, one for heating, perhaps one for outside functions and or garden lighting, and one or two spares... that's 6 to 8 circuits only !
Use any board you prefer.

Success

My $.02. Local availability of breakers from multiple sources.

You could install a 100 A panel in the garage and still feed it with a 60 A breaker. That would maximize spaces. You can also use one with a main breaker. e.g. 100 A breaker even if it's higher than the feeder and use it for a disconnect.

If your putting power tools in the garage, then you could consider two panels. One lockable for the machines and another for the lighting, door opener etc. That way when you leave the garage and if you have children, you can cut the main on the second panel and guarantee all the tools are off.

Just ideas.

My uncle had a detached workshop (also a garage) and the main breaker was in the garage which you had to enter to enter the house from the back. Every night, he would turn the feeder breaker off in the garage.

It's always nice to have shop breakers in the room with the equipment.

My high school had an start/stop key operated station that would cut power to all the machines.

Ideas. Nothing more.

Unless the garage is over 2000 sq feet big, be a little bit realistic : how many circuits will you ever have there? A 60 Amp board .... One for lights, one for wallsockets, one or two for machinery, one for heating, perhaps one for outside functions and or garden lighting, and one or two spares .... that's 6 to 8 circuits only !
Use any board you prefer.

Success

You are correct on the current usage requirements, but here is my thinking.
1) My next shop will be quite large. I would estimate 8-10 220 machines. I prefer to hard wire my machine than use a plug in a electrical box. I plan on removing this panel for my new shop in the future. Which will be 100amp.
2) You can always use less, but can't get more without replacing the panel. Difference in cost is about $50-$100 between 6 space and 20 space.
Example--
QO112L125G about 131.00
QO120L125G about 181.00
3) I don't see any harm in using a bigger panel.
4) I will need to replace the #6 wire for the 60 amp panel with #4 or #2 wire for the 100 amps.(Can't remember which one is the corret size, I think #4)

Seems to me the positive of the bigger panel out weighs the negative.