Back when at school I started with 35mm and once swapped for a Yashicamat for a weekend, later I bought a very early Rolleicord, followed swiftly by a pair on Mamiyas a C33 & C3. 120 they became my main B&W format. Then came 5x4 in my early 20's but used mainly for business/work.
When I began shooting more personal work in the mid 80's I became frustrated by lack of movements with my Mamiya 645's, so switched to 5x4 only using 120 for commercial work.
Then I grew up and bought a 10x8, it's a progression. I still use 35mm but only very occasionally, I've begun shooting 6x17 because I'd always wanted to shoot with a much wider format, and now I have a hankering to shoot square again, so have a Yashicamat and a Rolleiflex.
Ian