They are all equally customizable. You can change anything and everything.
But if you're asking which one is the more fashionable and easy to customize in current fashion, I totally agree with you about the Street Bob.
The Iron 883 and 48 are interesting as well.

 

Softails

 

I think it depends on your age and what might look good to your eyes. Any of the bikes can be "customized" to a personal taste. What looks good to me might look stupid to you and vice versa. I think that's why there are so many different models and colors to choose from.

 

Hey everybody, it's a pissing match.WOOHOO!!

 

I think that it is the Dyna Super Glide first and the Street Bob second only because it has a few steps already done.

I'm getting started on this 2010 SG.

 

Hmm..most customizable? No such thing. You're only limited by A) your imagination and B) your checking account. If you are wealthy in imagination then you can come up with anything you want and find the means to make it happen.