Honestly for your purposes I think that any good name-brand cordless drill will do, it doesn't sound like you need anything especially heavy duty (just heavier duty than the cheesy thing you have right now, no offense meant
). Ryobi is good but so are a lot of others. Pick something on sale that comes with an extra battery so you can have one on the charger while you're using the one on the drill. Make sure to get a drill with 2 speeds if you are sometimes less-than-perfect in your screw-driving-in technique
Have fun,
Pat
Have fun,
Pat