I look all the Cr cards available on the market and i cant say for sure its worth spending clintz on. Some are very weak in terms of attack, damage, ability, or bonus. Some are the exact opposite. When I look at the price, i think " is it worth spending millions of clintz on?" Look at the prices these days: its anywhere between 10000 to over 16 million.
Tell me what you think.
If you're talking about investing, go for powerful CRs in the mid price range like Jackie Cr och Tanaereva Cr. Those are pretty much bound to increase in value over time.
But if you're talking about making a powerful deck, there aren't many CRs that are expensive but also relatively balanced. The ones I can think of are Tessa Cr, Splata Cr, Marlysa Cr and Nahi Cr.