Here is an off-the-wall idea for a flashlight with a handle. Since you'll continue to get recommendations for traditional flashlights without a separate handle, and a lot of them are good recommendations except for lack of a handle, maybe a separate accessory handle would give you the best of both worlds: a well-made, traditional flashlight, plus a way to add a handle when needed. The best handles I could find were in the category of "camera handles", and come in all shapes, sizes, and prices, often as low as $10. They almost all mount to a 1/4-20 "tripod mount." Some (not many) flashlights have a 1/4-20 thread built-in, but most would need another accessory like the Solarforce SC-1 tripod mount (also pretty inexpensive--a black ring with a female 1/4-20 mount).
Keitho,
Great response!
If you wanted to get really custom, you could get a light that accepts a remote pressure switch (Convoy C8; Nitecore P30; for example), and mount the pressure switch to your handle for remote on/off while you're holding the handle. Depending on your setup, it could look pretty tactical, and would be 1-of-a-kind. It might push the budget a little bit, but it could be useable on multiple flashlights, and would probably out-live some of the cheaper flashlight options you'll be considering.
Good luck!