Looks - overall IS (modern aggressive) > TLX (clean lines and appeals to majority of public).
Maintenance - only fair comparison is dealership pricing on recommended scheduled maintenance items. I would suspect there won't be a huge gap here
Reliability - can't seem to find any long term testers on the web to provide some advice, but you do get that Japanese reliability
Fuel - really comes down to AWD vs FWD / RWD and if you go with turbo how heavy your foot is.
If I were making a decision based on value, model depending, leaning towards TLX, but hey you only live once. the IS is a bit pricier but also more appealing to me.