Since you said you don't have a theme yet I can't say for sure who you should get but I recommend O'hare or Papi and Canberra or Gala just cause I like those the most out of them (mostly o'hare and canberra lol) ^^
Bluebear for female, Punchy for male. But in all honesty, I'd recommend balancing out the personalities, if you can. You can have one or two duplicates, but if you want everything, try to get one of each.
Well out of those I would recommend Marshal or Punchy and then Bluebear I have both marshal and Bluebear and I used to have Punchy. They're all really fantastic but marshal is just so little and cute, it's probably that which has stopped me getting bored of him. I've had him longer than anybody else. Bluebear is great and have a lovely design to her, she's one of the few peppy villagers that hasn't irritated me.
Since you don't have a theme yet, I don't know who I should suggest, but here's a tip:
Look what their house exteriors are like! I usually decide my villagers this way.
Thanks everybody! Based on all of your suggestions, I've decided to go with Canberra for my female villager. I'm still deciding whether I want O'Hare or Punchy in my town for my male villager, but I'll make up my mind eventually.