I also use Hashflare, and currently have a 1 TH plan. I chose to buy 1 TH outright as for about $120 I would earn about $1 a day at market rates, minus fees.
I feel that bitcoin difficulty will pay out less and less over the next year, so wanted to recoup within the first 6 months. Thereafter everything is gravy!
That's very wise. Thanks for this :-)