I would go with shadow. It is the cheapest on your list.
The reasoning is that you are not going to know what you are looking at the first couple of times. It is very easy to buy a game that looks great, bring it home, and find out it has issues (cosmetic or otherwise). I am pretty sure alot of us will admit to missing things even after looking at a few dozen games. With shadow you aren't as likely to get hosed on it, especially compared to monsterbash due to its high price or tz due to its complexity.