Well......
They are not really all the same. There are balanced and unbalanced. With balanced ones there are the check-valve style and the one piece style. Some have a bolt, some don't. Some have metal parts and some are made from 100% Delrin.
When I wanted to buy one for my Pinnacle Evo2, I started to get educated. I decided on the Halcyon, 100% Delrin, balanced, one-piece unit. I liked all the above characteristics, plus the low profile design. It can be closed for times when I don't have it connected and there is no bolt to worry about losing or fumbling with underwter.
Now, as for the cataheter, you have to experiment to see which one you prefer...and that works for you. Rochester Medical will send out free samples of various sizes and types so you can try before you buy.
http://www.rocm.com/reqsamples.php
Also, take a look over here for some more umm..instructional information:
DecoStop Catheter Thread
Good luck!