GW seem to be getting better at mould lines as they used to be terrible on a lot of models
I've noticed that how bad they are seems to be in direct relationship to how long ago they last redid the sprues.
It's something I was speaking to my brother about when I did some of the latest Firewarrior sprues (the ones with all the drone variants on the sprue), which were almost mould line free compared to the previous ones I'd bought about 10 years earlier as part of the older set, which were awful, newer models that have been completely designed/made from CAD masters seem better as well (I'm guessing as they make the moulds differently).
Building my Titanicus models has been almost a dream in terms of how little clean up was involved (basically only where the gates are for most of the parts), but they're moulds that were probably at the beginning of last year* so almost certainly some of the newest ones they've made.
I think part of the reason they still have the mould line problem when a lot of companies don't seem to have it as bad, is that they've still got a massive number of models being made from sprue layouts/moulds that are over a decade old whilst a lot of companies change their line ups far more often.
Mind you the position of the gates on a lot of their models, especially resin is a major pain in the neck - iirc I'm sure one of the games workshop designers my brother spoke to at one of the events mentioned that they have to work the gates out themselves and I got the impression that it's something they can find problematic (probably a lot more so on older designs where the mould making techniques were more limited and it took far more time to try different sprue layouts, so they may have gone with the first one that worked).
I've been cleaning up a gatling blaster for the Warlord and it's gates are at the back end of the barrel merging into the alignment pegs so you have to do a very tight 3 way cut on each of the barrels to remove the gate, and the barrels get in the way of the cut as there 3 of them per part.
*Given the reports that they changed from their plan to do them in resin to plastic (thank god) very late in pre-production.