The version you get really depends on how much experience you've had previously and how long you've been away. Of course, if you've been out of the loop you aren't gonna want to jump right into something complicated like the P's or iDL, maybe a connection Tama.
- I'd say if you had a bunch of previous experience but have been away for a long while you should go with a v5, v6, or Tama-Go. If you're feeling like you can handle it MAYBE a +Color or iD. The newer Friends and Friends Dream Town are also fairly easy to grasp, as they're in English and their growth chart is already documented.
- If you've had a bunch of experience and it hasn't been too long, maybe thro in an iDL or P's into that mix.
- And of course if you've had minimal experience and it's been a really blong time I'd say your best bet is anything from the v3-v5
After you use the Tamagotchi for a while, feel free to jump into complicated ones like the iDL 15th anni, P's, 4U, or 4U+
Hope I helped C: