Baneslayer Angel is a cool card, but EDH isn't really the place for french vanilla beaters. Baneslayer is certainly a respectable beater, but it also doesn't really generate any card advantage or enable any synergies in a vacuum. As the saying goes, it dies to
Doom Blade.
That said, there are a few spots I could see it being played. The most obvious spot is any sort of angel tribal deck. A lot of the strongest angels are more expensive, but Baneslayer is very castable at 5 mana. Not a terrible inclusion for
Kaalia of the Vast as a beater that you don't always have to cheat out. Alternatively, throw on some Swords of X & Y or other equipment - flying and lifelink provide a very solid base of keywords to suit up, and five power of lifelink is pretty tough to race. Also a very nice suite of keywords for
Odric, Lunarch Marshal.
I'll also call out the incidental protections - demons and dragons aren't the most common creature type, but they do show up reasonably often. Could be an interesting tech card if there are a lot of demon / dragon commanders in your meta. On the other hand, if the protections aren't relevant, I'll call out
Lyra Dawnbringer as an alternative - mostly the same creature, but also has legend synergies and pumps any other angels you may be running. Meanwhile,
Gisela, the Broken Blade is a slightly smaller version with some incidental upside if you ever meld her.
....looking a bit deeper, I'm not sure what other beaters I would run over Baneslayer, assuming I'm in the market for a beater in the first place. Not really a topic I've done much research on. Maybe
Sunscorch Regent? Plus Gisela and Lyra, as mentioned. Hmmm...