A big consideration, when evaluating plans, is your budget.
I like the idea of a 50/50 split but only if you are planning on spending >$1,000.
If you're spending less than that or if you're just planning to play with the cards- buying packs will, probably, not work out very well for you.
For example: Summoners
There's ~30 Rares in CL, 5 of them are Summoners- which puts your odds of getting a summoner at ~1/6th in each pack. For the cost of 6 packs, you can (probably) buy enough summoners to make 2 L2 summoners, after General Sale.