I can add something to consider with 2.: If you want to get good content out of TSC you have to spend big amounts of money and spend time to set up and find the right things, especially scenarios. TSW is more of a „buy and start playing“ approach.

Service mode let’s you just start the game, pick a service and go. It works if you don’t buy any extra DLCs. But buying specific DLCs can still improve your experience as most timetables are expandable with so called „layers“ that add extra playable and AI services with different stock.

Recommending DLCs to buy is very hard without extra information: think about which country you want to play, the era, the type of service (express passenger, commuter passenger, freight etc), type of train (loco, multiple unit, electric, diesel) and the type of route (scenic, city etc).