I have used Professional's Choice SMBs for many years and I really like them. I have never tried any of the "knock-off" type brands, so can't really comment on them.
I have used both the SMB II and the Elite SMB. The Elite is a more tailored fit and I find them easier to use in conjunction with bell boots if desired.
I have never had any issues with them and continue to use them on my guy. If you are not familiar with their proper application, try to ask someone who is experienced with putting them on.
The Professional's Choice web site used to have small videos that you could watch in regard to correct application of the boots, but the last few times that I've been to the site the videos were not working.