The first.

German doesn't have a "th" sound (okay, technically it's more correct to say German has neither of the two "th" sounds as this is an important difference when pointing out that English only has one of the two German "ch" sounds and only in some variants of English and almost exclusively in Scottish words but I digress).

But based on my experience it's a coin toss whether German speakers who don't know enough English to be able to make an attempt at pronouncing it will go for "trottel" or "srottel" in that case, with the latter being even more likely if they go by ear rather than reading the word spelled out.