Yes, WP's are probably best because they have all the range bonuses of bases (at least in Gold they do) without the upkeep cost. Then again, you might enjoy mines... personally, I don't use them, but some people like them. You don't get quite as heavy mounts with WP's as with bases but I think the maintenance-free aspect makes WP's better (as well as the fact that they're NEVER on the "wrong side" of the planet!
)
The Massive Planetary Shield as it stands in the unmodded game is probably a waste of time - it's so darn expensive! AFAIK it doesn't prevent troop drops - maybe it should!
Some mods have other planetary shields, though, that might be worthwhile...