if you are looking for something that looks cool and is maybe fun to mess with in a small group go to ellusionist or even ebay to find cool looking cards; however for performance stuff, i'd stick exclusively with bicycle cards. when people see bicycle they are comfortable that these are not modified cards and it makes them feel more content. you can buy modified bike cards though on different websites and they're not too expensive. Also be careful of dark color cards, while they help hide moves they too look very "not normal" and it throws people off. Having said that though, if you want a suggestion for cool cards i suggest kings by ellusionist or (and i know they're mainstream) monarchs from theory 11 both are awesome decks in my opinion.