Which is better for concealing blemishes: Advanced Concealer (clinique) or Mac's studio finish spf 35?

Neither. When you use a concealer all you are doing is covering up the problem. You should start by finding a good cleanser and toner that works for your skin type. Get rid of the problem instead of covering it. I know you will still get some blemishes and it is alright to use a concealer for the occasional cover-up. If you are going to buy one anyway go with the spf 35. You should start wrinkle care early that way you don't have to fight with them so hard when they really are an issue.