I like the rubber coated ones. You can get the big 3 spoke stainless ones on eBay for decent deals. Finding a good knob was harder. I found one that you drill through the wheel so it nice and clean. I couldn't find a rubber coated 3 spoke at the time. Still can't find a rubber coated 3-spoke. I sold my last boat in a hurry and forgot to take it off.
Hmm can't find a picture on my phone, I have a 5 spoke now. I think standard size is 13.5".
Here's the steering knob I like, no brackets off the side to catch,
http://www.gemlux.com/catalog/steering-accessores/1504
It is being discontinued, I paid way more for mine when I got it.
Jason