I initially chose Canines and Other, but after consideration I removed Canines for the fact that even for me it wouldn't be that hard to get my hands on one, and the question was what species did you want to be for a day, not necessarily who you wanted to fuck ?
With that in mind I'd probably choose a Kangaroo, possibly the hottest species on the planet IMO, and any kind of reptile. I'd spend some time of my day doing normal stuff each species does but a fair amount of the day WOULD be spent fucking. I was originally thinking Kangaroo/dog but then I remembered it'd be pretty easy to fuck a dog and bearing in mind we can't have safe penetrative sex with practically any reptile I'd love to be able to have the proper genitalia for a day to have some harmless fun, as I do find some species particularly attractive. I may end up regretting it though and missing the experience ?
Leaning towards male but I wouldn't mind trying on some female genitalia either. I'd honestly love being any of these species but after certain considerations, if I had to pick only two, those would be it.