Model Grandpa,
From another grandpa. You're no stranger than anybody else here. For myself, I've been buying kits for 30 yrs and they're all 1/72, US Navy, Marines or Coast Guard. I get my diversity from the different eras represented, from post-WW I to current. Biplanes, props, jets, copters, fighters to multi-engine - that's diverse enough for me. I don't have the need ( or cash) to branch out farther. Many have said it - go with what you like.
If it weren't for us anomalies, this would be pretty boring, and how would we learn anything?
Regards,
Dick