Attaching Hood - Best Stitch?

[Limey]

Hi

I recently 'finished' a child's cardigan - except, that is, for sewing on the hood.

I love making hooded sweaters but detest seaming - could anyone tell me, please, which is the best stitch to use for this particular job?

The finished cardi is in Double Knitting (sports weight) and the second one I'm working on is Aran (light worsted weight).

Would Running Stitch be an alternative to time-consuming Mattress Stitch? Back Stitch is quick and easy but would it make a too-bulky seam on the Aran?

Any ideas would be greatly appreciated.

Many Thanks

Ellie