Bulgaria vs. Caucasus?
 

Bulgaria/North Macedonia vs Armenia/Georgia in May/June

Any tips on comparing these places weatherwise? My main worry is that mountainous areas like Rila or the Caucasus will be too cold/icy to access and should do either/both later in the year. On the other hand I guess most of Bulgaria should be nice in that time of year, Kazanlak should be good, etc. so would think only perhaps the higher mountains would be an issue.

There will be snow at Rilski manastir in winter, but certainly not in late spring.
Many parts of the high Caucasus (between Georgia and Russia) may still have snow.
All depends on the places you plan to visit.

We visited Rila in late April with no problems. It did not even cross our minds even when seeing snowcapped mountains from Sofia.

https://flic.kr/p/H3p4AW

https://flic.kr/p/HUY7oW

Amazing! Thank you, guys!