I've been using the Arista Premium Odorless rapid fixer. It's important to me that my paper fixer doesn't smell, because I have such a small dark-closet.
It seems to me that ammonium thiosulfate is ammonium thiosulfate, so one might as well buy the cheapest fixer available. It seems that the only qualities to buy on are price, capacity, and keeping ability. If capacity and keeping ability are better between brands of fixers, the more expensive ones might end up being cheaper in the long run.
I buy whatever fixer is the cheapest or on sale, fixer is fixer, I have a low volume operation, so I usually look for smaller quantities, the Ilford comes in 1L bottles, I have an empty 500ml bottle from years ago, and put half in there and seal it up, the rest I can usually use before it expires.
I use Ilford Hypam 1:4 for film and 1:9 for paper. Availability and cost are my main factors. Calumet sells it and it comes to my door within 2 days of the order. Calumet is a sponsor here as well. Calumet is a member of Upromise also and sometimes they have free shipping offers so I stock up then.
The ARISTA PREMIUM ODORLESS FIXER is a very highly concentrated fixer and is a "stop fix" as well. Therefore, if you like there is no need for a stop bath. If you prefer ODORLESS STOP BATH is also available.