bw1/2 starter choices

so i wanna do bw1 then bw2 as casual playthroughs but idk what starters to pick. ive used all 3 starters before so there isnt 1 ive not picked but i dont wanna pick the same starter for each game. ill also be memory linking via the unova link system then using something like pkhex to give me the unlockables the other version of bw2 i didnt pick have so i dont miss out on things