Tyco’s drive unit…well, sucks. I’ve had good luck repowering the RF16s with F9 chassis from Bachmann. As for Tyco freight cars, if you remove the couplers from the trucks and body-mount them, they aren’t that bad.
A Tyco trainset was my introduction to HO back in 1971. Tyco was owned by Mantua, Mantua had been around since the forties, then somewhere in I think the sixties began selling their cheaper stuff under the Tyco brandname (Mantua’s owner was named Tyler - TYler CO = TYCO). Eventually it became just Mantua again. The Tyco 4-6-2 I got in 1971 was a RTR version of the Mantua kit that had been around since the Korean War years.
A couple of their cars can be used for some pretty nice rivet-counting-level kitbashes, too. The new Prototype Railroad Modeling journal that Speedwitch Media began publishing late last year has an article on kitbashing a Minneapolis and St. Louis URTX reefer that uses the sides from a Tyco reefer.
Just shy of 20 years ago, there was a Cyril Durrenburger article in MR on how to kitba***he Tyco/Mantua steel gondola into a prototypically accurate gondola for a few railroads. I seem to remember the Wheeling & Lake Erie and the Texas & Pacific being two of the roads that had cars that the Tyco gon worked well to make. The cars he covered in the article were all very easy projects to make into highly-accurate models.