Depends on your budget. The Mk 6 1-6 is supposed to be the bomb. It's also about $2K plus mount. Below that, again staying with Leupold, you're into the VX-6 multigun, then VXR-Patrol, both using the Firedot reticle. They're about $950 and $550 respectively. You mention the 1.5-5, which would be the Mark 4 scope. However, having previously owned that scope I would advise against it. I had the illuminated SPR reticle model and found it to be a VERY poor compromise. Not fast enough nor precise enough. Truly the worst of both worlds.
If you're willing to look outside the Leupold brand, the Nightforce 1-4 FC-2 is VERY good as is the Swarovski 1-6. Lots of guys like the Vortex 1-6 also, but it's VERY heavy.