2.8L is a lot better to buy used as they are more robust than the 1.8T's.
The 1.8T's have a lot of problems if you don't run synthetic in them and a lot of people didn't. The 1.8T can be easily modded where as the 2.8 isn't practical to mess with.
Most 2.8's use a little oil, but it shouldn't be more than 1L per 5000km or so. Expect it to suck on gas mileage.
The 2.8 should be pretty problem free for you if you get it properly inspected first. My buddy has 290,000kms on his 99 2.8 Automatic.
2017 VW Jetta 1.4T (winter car)
2010 F-350 Nortruck Tool Shed
2007 BMW 5 (Wifey's)
2004 Audi A4 1.8T 6spd Stage III w/ Meth
1985 F-250 6.9L IDI w/ATS turbo