I have been doing a lot of researches on who has a better benefit.
So Far I am still confused as ever.

Long story short, if I want to purchase something from say... Banana Republic.
I have the option to link it from the Venture Card partner site and get a total of 7 miles to a dollar, or I can link it from Skymiles shopping and get a total of 2 miles to a dollar.

But when I need to book a flight, say LAX - LHR, say May.

Using Venture it would cost roughly 87100 miles.
While it would only cost 60000 miles + $178 tax/fees.

Which option of purchase route would save me more money, and gain me miles? From my understanding, Delta Reward tickets do not earn MQM? I know the ticket I get from Venture would earn full MQM. But not all merchants bonus point ratio is as high as the one mentioned above. usually it's about venture:delta = 2:1

Anyhow, if anyone who can shed a light on this to help me and give me a better perspective, I'd greatly appreciate it.

Thank you