As you mentioned in your post, I would definitely consider a model that can accept a light, either with a rail, or a model that can take an alternate-mount light, such as Streamlight's smaller TLR models.

Given the fact that you are wanting a defense gun, I would certainly look for a rail if possible, and definitely get or add night sights. I think a light is a must with a defense gun (either quality handheld or weapon mounted), as are night sights. For a gun that could be used in a home defense capacity, you should plan to have a gun that is fully capable in low light scenarios, that allows for positive ID's of targets or possible threats in less than ideal lighting conditions. Personally, I also have a combat flashlight stored with my firearm, for white light redundancy (as well as for searching, navigating, and identifying purposes) - it's that important. We often can't control or dictate whether a use-of-force encounter happens in daylight or low-light, but we can prepare for both lighting conditions, and it is something that is important to do when considering home protection and self defense. If you ever should end up in a position where you might have to use your gun, the ability to ID and know what a potential threat is doing is critical to deciding the appropriate course of action, and in low light, you need the ability to see well. I would plan and budget for a weapon light / and or a good combat light and night sights with whichever model you choose.

If you end up choosing a Glock model, I'd also suggest springing for the MOS version - if you ever want to add an optic, it will save you a bunch of money on slide milling costs. While they've already exploded in popularity in the last few years, IMO optics are going to continue to gain major widespread use on handguns going forward, especially with all the very reliable, small optics available and new offerings coming to market.