I never saw the 1-6 HD broadcast so i cannot comment on it.

To me if i must watch the prequels this is the viewing order.

4-6 oot

1-3 prequels typically the theatrical versions which are not dvd quality.

I found that the prequels were a lot more enjoyable as a complete media experience as stand alone movies they fail, Lucas is a terrible writer. The novelizations which are also unabridged audiobooks, the comics and other fill in the blanks EU. Which again would not have been necessary if Lucas hired a team of writers on the movies.

Conceptually the prequels are not bad. Lucas played to his strengths which are primarily the visuals. The Characters needed to be more well fleshed out. In the movies they are more vehicles for a concept and Lucas musing on Religion and Politics than they are real characters.

I mean he probably had a very basic outline that said certain characters did certain things. Lets pretend the outline was 3 pages long, has to create a background story that fits with what we know from the other 3 films and add exposition.

The prequels feel very hastily sketched out, at least episodes II and III are that way. I know Lucas spent a lot more time on pondering episode 1 and writing its script, which the final result does not show.