You can choose whatever you want. The important thing is to know how much performance headroom you have, and your achievable frame rate without ASW, so that you know which ASW setting will work without choking.
The way to do this is to turn on the Performance Overlay HUD, which will show you the realtime framerate as well as performance headroom. Launch the sim, activate VR, and load up to a place that puts the highest demand you expect to encounter (e.g. plane, weather, city density…) Then, with VR still active, click the ASW mode drop-down in OTT and disable ASW completely. Now take a look in your headset and see what framerate you’re getting. This tells you which ASW setting you can use and get stable performance. For example, if you have the Quest’s refresh rate set to 72Hz, and you want to use the half-framerate ASW lock (it’ll be called Force 45Hz with ASW which is a misnomer, it’s really half the refresh of your headset), then you need to have a base framerate greater than 0.5*72Hz = 36fps. Thus you need to make sure your framerate stays consistently above 36fps at all times, to be able to use the Force 45Hz ASW option.
I realize that sounds confusing but it’s really pretty simple. You need to make sure you can attain a framerate consistently higher than the fps you want to lock ASW at, or it won’t be able to do its job without dithering to an even lower rate. You do this by turning off ASW completely, seeing what framerate you’re getting, and then lock ASW to a framerate less than that.
By using the performance overlay HUD I mentioned, you can see on the framerate graph what the ASW lock options are doing, too. When it’s enabled, you should see a very flat, stable line at the value you chose once ASW is enabled. If it’s still jumping all over even after things have finished loading, then you need to dial back the performance demands somewhere else, or lock ASW to an even lower value.