While you can't really go wrong with a Bushmaster, you might be better off with another model. The M4A3 is a really nice *looking* rifle, at it's no slouch at shooting, either, but in my view, too many of its features are purely cosmetic.
1. The tele-style stock is more form than function, as it saves practically no weight and is, IMHO, not as comfortable as a standard A2 stock. In addition, a standard stock gives you room for storage. It looks cool from a distance, but in my eyes, if it doesn't function, its a toy!
2. The Mini-Y compensator, while highly effective, features rear-facing ports which direct gases rearward in the immediate vicinity of (if not directly at) the shooter. Muzzle brakes/compensators are loud, but this design exacerbates the problem. It is true that given proper hearing protection, this isn't a tremendous problem, but it may be if you are visiting a smaller range, or need to shoot without proper protection (i.e. home defense).
3. The noise of shooting AR15/M16s never bothered me at the range (even when using POS mil-issued ear plugs), but why increase the risk of hearing damage when there are better alternatives? There are alternative muzzle brakes available, but...
4. The 14.5" barrel creates limitations on the choice of available muzzle attachments. The attachment must yield an overall barrel length of 16" for legal purposes. Kurts Kustom Firearms makes an extended brake for this purpose. If however, you come to decide that you are not comfortable with/don't like muzzle brakes, you will still need some extension installed to make the barrel a legal 16". Why not start off with a 16" upper (M4, Hbar, or Superlight), then allow yourself the opportunity to decide whether or not you want a brake attached.
I myself have traded in my 14.5" M4A3 for Bushmaster's 16" M4-profile upper with standard A2-type lower. The 16" should be more effective overall, and if I want a brake I can always add it later for $100 or less (installed).
Again, you really can't go (completely) wrong buying any Bushmaster, but some are better choices than others. Which ever one you choose, enjoy!