If you are looking for true portability in 6x7 or larger you really can't beat a folder. They fit in your cargo pants pocket' use 120 film n are real cheap... Even cheaper if you DIY restorations.
Anothe overlooked 6x7 that has made me a fortune as a wedding photographer n has served me right to this day as a beautiful take along is the Omega Rapid. It's a fun camera to use.
Then my street shooter is my trusty 645 ETRS. Beautiful negs n a system can be had for $300.
If weight is a concern... Yashicamat 6x6! Dirt cheap n so much fun to use. Beautiful camera at a bargain basement price.