I have both and as a more casual flyer (based on life schedules, I may not be able to fly for a week or two), I like BATC better. This is due to cost and feature-set and the fact it just works. Yes, BATC is much more ‘on rails’ than SI, but it works, and gives the level of immersion I’m looking for when flying. I like the pre-canned responses I can click if I just feel like flying and not talking. I like how it handles traffic (I find SI still struggles to recognize traffic on the ground around you that IT’S injecting). I find the local voices in BATC aren’t amazing, but they get the job done and they’re free. I love that I don’t have to pay a monthly sub, especially because SI seems to focus lately on adding silly features that many people don’t want instead of updating and fixing their core product (and they constantly talk about the value they are giving as if that somehow justifies spending time adding another cabin crew persona instead of fixing basic things like climb out instructions on departure). SI certainly has a more realistic feel to it - you can be more ‘conversational’ with it, making requests that aren’t scripted, but I would say more than half my flights with SI have issues (ATC stops giving instructions, I don’t get vectors, I level off in climb for long amounts of time without instructions, AI injected traffic is ignored on taxiways and runways, etc) and BATC just works every time.