Distinguishing between z3 options in homebrew - homebrew

Question

In homebrew, if I choose to install z3, I get the following result:
▶ brew install z3
Error: Formulae found in multiple taps:
* homebrew/science/z3
* mht208/formal/z3
Please use the fully-qualified name e.g. homebrew/science/z3 to refer the formula.
On one hand the homebrew formula might seem to be more canonical because that's the main repository (or whatever one calls the top-level item in homebrew), but on the other hand mht208 is the developer of z3 as near as I can tell. Is there an easy way to determine which of these two has either the latest version or the most stable version?
Edited to add additional information:
When I run brew info on each fully-qualified name, I get the following results:
▶ brew info homebrew/science/z3
homebrew/science/z3: stable 4.4.0 (bottled), HEAD
A high-performance theorem prover
https://github.com/Z3Prover/z3
/usr/local/Cellar/z3/4.4.0_1 (50 files, 38M) *
Poured from bottle
From: https://github.com/Homebrew/homebrew-science/blob/master/z3.rb
▶ brew info mht208/formal/z3
mht208/formal/z3: stable 4.4.0
https://github.com/Z3Prover/z3
/usr/local/Cellar/z3/4.4.0_1 (50 files, 38M) *
Poured from bottle
From: https://github.com/mht208/homebrew-formal/blob/master/z3.rb
==> Dependencies
Build: autoconf ✔
==> Options
--with-ocaml
Build ocaml bindings with the ocaml from Homebrew.
--with-opam
Build ocaml bindings with the ocaml from OPAM.
So, in theory, these both seem to be the same version (4.4.0_1), except that the mht208 version has some options and depends on autoconf (which is already installed). This also leads to the question of whether it makes a difference how the ocaml bindings are built (both ocaml and opam are already installed).

Answer 1

It's pretty easy to take a look at some more information via Homebrew:
$ brew info homebrew/science/z3
homebrew/science/z3: stable 4.4.0 (bottled), HEAD
A high-performance theorem prover
https://github.com/Z3Prover/z3
Not installed
From: https://github.com/Homebrew/homebrew-science/blob/master/z3.rb
This shows us that this formula contains version 4.4.0, that it's bottled, and that you can install a HEAD version (via brew install homebrew/science/z3 --HEAD).
Taking a look at the other formula:
$ brew info mht208/formal/z3
mht208/formal/z3: stable 4.4.0
https://github.com/Z3Prover/z3
Not installed
From: https://github.com/mht208/homebrew-formal/blob/master/z3.rb
==> Dependencies
Build: autoconf ✔
==> Options
--with-ocaml
Build ocaml bindings with the ocaml from Homebrew.
--with-opam
Build ocaml bindings with the ocaml from OPAM.
We see that there are now options available to this formula that aren't in the other one. Now, we have no idea if this is because of different defaults or whatnot, unless we actually go and take a look at the formulae. Here's the homebrew/science one (very simple formula, essentially just calling make install), and here's the mht208/formal one (much more complex).
They are both the same version, so as far as stability goes, I'd say it's a toss-up. The Homebrew people do a great job at what they do so in general I suggest to others to stick with Homebrew unless you can demonstrate a problem in the software that is not being addressed. Of course if you can, it's usually not too difficult to get it fixed in the mainline Homebrew repository. :) If, however, you need the more complex capabilities of the second formula, (building ocaml bindings and whatnot) then you should, of course, use the second formula.