Not to be confused with the "best" or number 1 test team. Which team do you find most impressive given external factors like economy and politics. I am going to say Sri Lanka outright here for producing the number one wicket taker of all time and the number one batsman(who happens to keep wicket) for a good period now. This despite a civil war that recently ended and could no doubt have had a traumatic experience for numerous players that we are oblivious to on our television screens.
I am not a patriot to South Africa in fact I detest my country since illness and for continuing to bring politics in to our cricket (and rugby) and f**** up team spirit and dividing support for our national teams along racial lines. Sport is one of the few things that can build a nation. Combined with the fact that SA seem to be the sole victim of an exodus of professional sportsmen to other countries. These are not just players that leave, but investments in terms of training and resources for players who have little regard for the country that nurtured their talent (screw it I am also not a patriot like I said) for this reason SA get's my second vote.
My least impressive teams are India for having a billion people who love cricket (almost all of them), but can't find a decent all round bowling atack and rely on doctoring pitches for their benefit.
Second worst is England for being the pioneers of the game and not finding their own talent, relying on other countries to develop and invest into future players for a love of money.