Okay, so for your first 5* team, I would suggest leveling the most versatile heroes first- since they’ll be your only 80 heroes for awhile. It’s difficult to say who when you don’t have a full team of 5* to pick from, in order to plan your ascensions wisely. For instance, you don’t want to ascend all utility heroes for your first set- I would suggest only doing one or two and making the rest more offensive heroes.
Zimkitha would be a good utility hero to ascend to 80, but since you’re leveling Rigard currently, her cleanse isn’t quite as vital. Although, she is fast compared to Rigard’s average, so she has him beat there. Her buff is also awesome to have at fast mana, so out of the two lions, I’m leaning more toward her. Though, if you plan on running Rigard for a good while, she might not be the best fit.
If you do Azlar, his SS will max at 80, and since he’s all about attacking- he really needs to be maxed to reach his full potential. Whereas Zim could sit at 70 and most of her skills would work just fine. Only thing is, I would only ascend one slow hero to 80 for your first set. If you have too many slows on your team, you may struggle a little more. Thankfully you have Sartana for at least one fast sniper.
Now, Mitsuko might be helpful at 80, but she’s too new to really know for sure. If she becomes another option for you, I would wait until people have played her some more, or maybe level her to 70 yourself and see how she fits on your team. Overall though, I think she’ll be a great hero for offensive and defensive raiding.
This is your first 5* going to 80, and because of that I would be sure before taking them there. You want someone that will help you almost everywhere. Zimkitha seems like the best option, but not my favorite choice. Her cleanse is amazing, but only really is necessary during raids; she can be substituted for dotes everywhere else. For Titans, she could be helpful because of that buff though, but Azlar’s tile damage would be better than hers. & I’m really liking the idea of Mitsuko, but it’s too early to say for sure.
Overall, if you’re itching to ascend a red immediately, I would do Zim for a safe bet. That buff and cleanse will find plenty of use. If you’re willing to wait though, I would until we see Mitsuko’s place in the meta. Who knows, she could be really amazing. & Azlar is awesome, but I’d rather ascend him as your second red 5*, since the slow isn’t as versatile.