Hi & welcome to the 'Place'. Looks like you've done some research. Good on you.

Of the razor brands you mention I like the T.I. but as you've seen a good one can be had from any maker as well as a bad one. Maybe look for a seller with really good after sales service. ?

Any reputable strop brand will do the job & longevity may just come down to whether you slice it or not .
At this point an initial strop purchase or any purchase may not be your last.

Simply avoid 'cheap' with leather.