Mate, first welcome to SC.
IMO, there really is NO best rifle, its what you the shooter like best, what fits you the best and how it fits the intended role that you have for the rifle. There is a big different in price between both those rifles. The XCR tactical I THINK is more accurate then the Tikka and if you wish to customise the rifle then is the rifle that you should get. There is a serious lack of after market parts for the Tikkas and that means that customising them is very tricky.
How much shooting experience do you have?? If little to none. I would forget a .308 for the moment and buy a .22LR to learn the basics. I did and dont regret it for a second. I have a nice little CZ 452 Deluxe and its a really nice rifle and very accurate.