I would like to know which one better and which can be taken off and be put back on with damage?

Most use a peel washer.

My understanding:

Peel washers:
Look better (matter of opinion)
Are a set length (thickness) deal, so once you have the timing right (the correct number of peels), you should be good to go indefinitely.
BECAUSE they are a set length thing, they don't keep pressure on the accessory very well.  Meaning, the FH might unscrew it'self as its shot.  Many people end up using loctite on the threads for this reason, making the ability to take on and off easily void.

Crush washers:
Easy to install.
Keep pressure on the FH meaning it will stay on without loctite.
CAN effect accuracy if they end up putting scresses on the crown.

I tried to get a peel washer to work, but after heating it up, I put the razor blade to it and snap... all the peel layers came off at once.  I tossed it, put my crush washer on and haven't looked back.  However, I was suggested to crush the washer some, meaning tighten it down, then loosen it, do the same until you only have a moderate amount of torque on FH (meaning less streses on the barrel)...

Hope this helps.

Gundraw

P.S. If you have more questions, the search and archive will give you LOTS of info.  That's where I got info when I was deciding.

Peel washers can be used multiple times, while it is recommended that you change crush washers each time the flash suppressor is removed.

Gemtech specifies that a peel washer be used for attaching the A2 flashider to mount your HALO on.

They say the way to use a peel washer is to hang it from a wire, heat it up with a propane torch to delaminate it.  Then, use the appropriate number of 'peels' to get the FH to time correctly.  The also recommend ceramic thread 'loctite'.