Total Recommendations: 3
Both centre around a story of demons. It is also rumored that Astarotte will make an appearance in Disgaea 4. Making her an honorary Disgaea demon. Though ironically, for the synopsis of this show, other than the sexual rapey stuff, which is mostly only implied and lightly hinted at for most of the show, the Astarotte demons are on the whole, much more 'normal' and more ethical than the Disgaea demons, showing a much greater tendency towards kindness and human morals instead of backstabbing, than Disgaea. Still, each of these might be appealing to you if you like one.
Both shows have a similar art style. And are about what might be seen as a "bratty" or somewhat self centred person in both cases. Panty and Stocking being about "Angels" who could care little about others. And Reinya as a master thief. Both seem to have a pet in which they abuse, as well as the general cast, and their exploits are all played up for grandeur. While Kaito, in contrast, on the other hand, is just yet a promotion of an idol in the idol industry, and isn't near so crass. It is filled with the limitations of idol, which are actually surprisingly high for it's source(the industry largely centres around innocence and moe). While Panty & Stocking holds nothing back in terms crass humor and playing the lack of innocence of it's characters on all levels, even taking very forward jabs at the idol industry.
Minus the ecchi, So-Ra-No-Wo-To shares a lot in common with Strike Witches. As well as it shares in common with K-On and Axis Powers Hetalia.