I have a 2008 jeep wrangler unlimited sagar and I'm wondering if I should lift it and put big tires on or just get big tires with no lift

It all depends how much money you want to spend? I would start with the tires. You can always ad the lift later if you don't like the look. The lift costs a lot more because of the labor involved.

It depends on how big you want your tires. You can run 33s without a lift on a complete stock jeep. Once you go bigger then you must start looking at a lift. Thewieght of aftermarket bumpers or a winch will also play a part due to sagging.