The reason they cannot mill the deck is because the cards and clans that can do that do not EXIST. If cards that had the ability to mill the opponents deck, yes it would be added. But there ISN'T. And we do not MAKE Vanguard cards, we only add them in as Bushiroad creates and releases them. Therefore, if you want decks that can mill the opponents deck despite how strong that would be, go email Bushiroad. We cannot introduce this mechanic because there is no official card or clans that utilize it, therefore it is not able to be added in or used at all.

There is no mechanic like this in Vanguard, therefore it is not necessary. You are asking for something that doesn't need to be in the game and would only bring stupidity. If Bushiroad does eventually make a Vanguard clan or a card that has the mechanic of milling the top cards of your opponents deck, yes, it will be added. But is there anything like that in Vanguard? No.

you can already mill your deck already if you didnt notice

Revenger Shadow Paladins because they are pretty versatile. (Field disruption + restand + mass draw/search engine)

The Royal/Shadow Paladin are the easiest, noob-friendly clans with massive amount of both offense and defense.

Like Zeon recommended, SP is the best clan in terms of mostly, everything. Draw power with SBs and Aurageyser to build defense. Diablo and Abyss for massive offense. etc.

Another Option could also be Dragonic Overlord The X decks. Since It is a deck that uses restanders with pretty good retiring abilities. And their defense is normally solid. a good starting clan would be Gold Paladins since they are able to effectively deck thin with their abilities while building nice columns but they dont have much control over the opponents field

Spike Brothers is an aggressive deck that can keep attacking from the rear guard, usually by returning rear guard units to the deck & calling new ones to replace them. This deck tends to work better closer to late game, but it is able to keep up the pressure. http://eternalflamesvanguard.blogspot.com/2014/05/spike-brothers-bloody-orge-break-ride.html is the link to a really good Spike Bros deck that exemplifies what the clan can really do.