Yeah, a T5 without a reflector is probably fine. A T8 with a reflector would be fine as well.
As for the basking bulb, you need to be really precise with halogen flood lights. They can get the temps really high. I'm using a 60w halogen mounted outside the viv, at 13" away and with it at 60% power it gets his basking spot to 105 F (110 F being maximum recommended).
I've seen these bulbs as low as 45 watts. If you get a halogen you definitely need to get a dimmer and a digital temp probe and you need to test it out without him in the tank.
I would say that there isn't a really big difference in heat area spread between a halogen and a basking spot bulb. The thing that makes the biggest difference is distance. What makes a halogen able to provide a broader area of heat is DISTANCE. You can put a 60 watt halogen 2 feet away from the basking spot, run it at 100% power and provide a nice good wide area of heat, but if your bulb ix FIXED at a close distance like your is, then you aren't going to have this benefit, so, IMO, if the basking bulb you have it working for you then just stick with that.
I'm not a fan on interior mounted lights, because for one thing I think they are generally too close. You can't really move your light back and moving it back is what you have to do to get a broader basking area.
So, yeah, I think, given your setup, the traditional basking pot light is fine. A halogen may be too powerful in that space. Even a 45 watt may need to be dimmed.