Hi, I like T205 and T206s because in the case of the T205s the gold border and T206 because of the poses/color mostly...The advantage to these is that they are pretty mainstream and plentiful compared to more obscure sets so I can get my "fix" pretty easily...
If you don't want to put the $/time into trying to complete these you can do team sets, back-sets, or other "sub-sets" and feel the sense of completion that way...