That's like asking which gold fish is better for your dresser. Lift allows you to put larger tires under your vehicle and have a higher ground clearance and in no way takes away from your engine power/efficiency. So a better suited question would be "At what size will new tires start to have a negative correlation with my engine size?" Well, I have a V6 AWD and am running 33" tires on 20" rims and I still have enough get up and go for the size vehicle we have. Gas mileage is a thing of the past, but who cares, I'm in a jacked up Commander!! But with only a 3 inch lift (Which is an odd amount), I don't see you putting much more than a 31x12.5 tire under there without rubbing. And stock is probably around 29.5-30 inches, so you won't be losing a significant amount of power from your engine.
Also, how do you plan to achieve 3 inches of lift? Make sure you read up on this. The 3 inches can be very bad for your geometry and cause major driveline and suspension problems more quickly than a 2 inch Budget Boost or a 4 inch Rusty's system.
New to the XK but not new to 0lllll0's. 06, Custom built light bar with 2 Hella 500ff fog and 2 Hella 500ff driving lights, Surco rack with 4 Hella 500 Fogs, 6" Lift, 17" JK Rims and 33" Cooper STT.