Should I switch from PSA to SGC for my Monster?

[AMBST95]

I know you mention wanting to display the cards. If displaying openly, either will be impressive. We're talking about a display of T206s. The black border is nice on SGC, but I'd go with who you feel most comfortable with. There are definitely a higher population of PSA cards. As a result, there will be more variability to sift through and you'll still need to be patient in building your Monster, irregardless of who you chose. If going SGC, you may need to wait longer to find a card you need. No matter who you go with, you'll second guess it multiple times in your quest, especially if you're struggling to find a specific card in one TPG and it's available in the other. If you like the cards you have, I'd stick with what got you started.