Old vs new tdi

Hi I've been driving a 1999.5 alh jetta (stock) for 3 years and before that for 3 years I owned a 1999.5 alh golf with upgraded clutch and Malone 1.5 tune. Had more power in it but all electronics failing so for my jetta I went bone stock and basic roll up Windows and no upgrades. Now I'm debating buying a newer model with more power as I want to tow a 1000 pound pop up tent trailer on long trips. I can do it with my jetta, but when driving on the highway I drop to 80 and have to go into 4th gear when climbing steep hills. So basically I'm wondering if the newer models are as dependable as the alh.I have 522,000 km on mine.
Thank you for any ones time .

Old vs new tdi