1st Thing to check is the throwing Ratio and the distance you can put your projectors.
as closer you can get as brighter will the projection be at same Lumenoutput from the Projector.
There are several distance-size Calculators online to check for more or less any projector available.
When you dont mind 2nd hand especially in Projectors there are many great deals in the 2nd Hand market ebay, regional sale pages etc.
I found most people use a regular Short Throw projector as they dont need too much distance but its still easier then to setup an UST. The Problem with Ultra Short Throw is that for Mapping you have a way smaller Area where your picture is sharp. So throwing on 3D Objects can cause Sharpness issues.
When you use a Standard Projector you need to be sure you are able to set it up without people running through your projection all the time. If thats not the case - Bravo then your options are endless. I think 4000 Brightness is more then enough for a nightly effect projection in the private area. another option could be to buy 3 smaller LED projectors with less Lumen and create a scenery with them so each could be setup on an individual object and you just have more flexibility.
In general i would not go for Laser as at the moment you just pay more to get the same effect. Yes Laser Source will run 4-6 times longer in its lifetime but when u use ur beamer only for projection here and there the difference doesnt matter. Kontrast Ratio and Stuff well i think thats nice to have to be great there but its not the main aspect of what creates the "Wow" Effect for the viewers.
Me personally i just recently bought 4 pieces UST LG Addagio 65LS Projectors as Warehouse Deals for around 500 each. Super Small. LED Light Source. Light Weight, FHD and looks great even its just 1000 Lumen each. So if you would have for example 3 of them you could probably cover more or less your hole Garage without any Trapez Correction. just create a 1 meter closed Zone where nobody can enter and u put them right in front of the Garage and all people could watch and walk in front of your projection without to disturb it.
Just think about wich aspects are important for you and then do ur selection based on that. I think brands doesnt matter so much. You wont go wrong with any Optomo, LG, Sony, Vivitek, Acer, Panasonic, Samsung. whatever. - Hands of Chinese Wonder Spec projectors...
Beside that in the area of reliable brands check if the Specs meet what you need and choose the best offer for you.
Greets from Spain!