For this kit, a sling or shoulder bag is a sensible choice if quick access is the priority. From the suggestions given, the Lowepro Slingshot and Tamrac Velocity 8 both sound well suited: sling-style bags can be rotated to the front for faster access, and users noted good comfort and enough room for a DSLR kit plus accessories. The Lowepro also has a built-in weather cover and some extra space for small personal items. The Tamrac Velocity 8 was specifically praised for comfort and for being easy to move out of the way, with optional accessories like bottle or filter pouches.

If you prefer a more traditional shoulder bag, the Think Tank Retrospective 20 was mentioned as a strong match for your requirements.

The key is to verify that the interior depth and length fit your DSLR with the 70-200mm f/2.8 attached, since that combination is bulkier than most standard zoom setups. If one-handed retrieval matters most, prioritize a bag with a wide top opening and minimal flap or zipper resistance.