I prefer "Aleene's Fast Grab tacky glue" for securing most, small to medium, Intarsia pieces because it sets up quicker than her original glue, in the brown bottle; therefore, i can move on to placing adjoining pieces without trying to hold sections together with tape or weights.
When putting backers on projects, or gluing large pieces that require a large amount of glue, I use Titebond II and hold in place with 25# bags of Shot until glue dries.
Titebond II is what i happen to have on hand, because a project i worked on about six months ago required the glue be waterproof. Any good carpenter's glue, for normal projects will work just fine.