They all have their pros and cons. The window mount is great (all of our Snowy Owl photos were taken with it), but it is slow to set up and somewhat fiddly in use. The astronomy tripod is useful only when you have a fixed setup, like the House Wren videos here (in which case the fine adjustment knobs are great), but it can also double as an expedient monopod in a pinch. The fish bonker (a 1/4"-20 bolt epoxied into a 1.25" thick dowel and cut and filed to length, with a tape grip and a cork pad added for good measure) works perfectly in our car. And of course nothing beats a full tripod outdoors.
We take them all with us on every trip - you never know what situation will come up!