"I would mainly" is a correct and usable phrase in written English.
You can use it when you want to emphasize that something is the dominant factor or most important aspect of a situation. For example: "I would mainly focus on improving the company's customer service."
"When I started this journey I thought I would mainly charge at people's homes and whenever I get a charging station that will be a bonus," he said.
I know, however, that if I were to be hit by a bus this afternoon I would mainly be remembered as the "Pizza Express guy".
That being said, the Nordics rate well on every list of sustainable companies in their respective sector, so I would mainly say, invest Nordic!
To give her that chance, I told her that I would share what I wrote up with her before I published it, that I would send her the audio file of our 90 minute interview and that I would mainly be asking her three questions and try to facilitate her saying what she needed and wanted to say.
I would mainly recommend starting off in the low numbers, so that people get even more dragged in.
"It matters to me so much more than I thought it would, mainly because I'm not stressed all the time about having no money," she says.
OK, I could have read non-fiction about it but I suspect it would mainly, if not entirely, have been by non-Indians, if I can use that word.
I'd mainly go to my closest friends, because they always help me through it.
But now, watching Dad, I realized that I'd mainly discovered what a solid thing an identity is.
I'd mainly been concerned then with getting down some of the things we talked about that evening.
The iPad is making a big dent in the home automation field just like I thought it would mainly because it offers so many more advantages over the traditional remotes found in the space for a fraction of the price.
