Splenda seems pretty OK. They've been studying it for about 50 years and all of the "bad" aspects that have come out in studies haven't held up in further studies. PubMed has an infinite amount of articles on it if you feel like reading. I wrote a paper on it a few years ago and from what I found there was nothing wrong with continued use, and the biggest gripe was about how artificial sweeteners "trick" your body and have the same effects as sugar since it tastes sweet, so your body assumes it is sugar. That was total shit though, with that said I wouldn't go nuts and have 50 packets a day. I would say Sucralose would be fine too since that's basically what Splenda is (Maltodextrin + Sucralose).
Stevia is good if it's actual stevia and liquid (most powders are mixed with other shit and a lot of commercial stevia is lab engineered based off stevia, the liquids are generally just straight up exctract from the leaf itself). Although with Stevia you have to be careful Walt hasn't dipped your pack with Ricin.