The design works I do for my current companies are either confidential or not 'good enough' to showcase. My best bet is to spend time working on my personal projects so that I can properly capture my skills and aspirations. Would a portfolio consisting of mainly personal work and no 'proven industry work' be of any value to top companies?
This is a problem that I've encountered in a fair amount of candidate profile and that isn't easy to tackle for sure.
First off, make sure that there isn't something you can get from the projects you consider "not good enough". Something that seems of low value for you might be of value for a recruiter. The challenges you faced, the compromises that you had to make and the solutions you found thanks to the process you put in place might be interesting, even if you do not like the final result. Don't cut interesting lessons and valuable experiences out of your portfolio if you can identify even a small value.
Secondly, "confidential" project might be ok to show during interviews, especially if what you've worked on doesn't overlap with the interests of the company your are interview for. You might want to check (if you can) with your current leadership to know what you can or cannot show to a private set of people, as long as you do not put it online publicly. I had a lot of candidates showing projects (in agreement with their current manager) during interview panels that were confidential. Some also go to the extent of showing only pieces of projects or part of their process instead of showing the finalized product. This is of course a sensitive subject so the rule is show what you truly can and don't show if you have any doubts.
Now for your actual question, the answer depends on what is defined by personal projects. Passion projects have great value during an interview panel and show your interviewer what kind of person you are via your interests, even if they are only slightly related to the job you are applying for. Personal projects made for your friends or family using skills that you apply to your current job is also of value.
But I'm assuming you refer to "skill training" projects for which I can identify two categories:
- Non-requested redesign of applications or websites. These are a double edged sword. On one hand it shows your commitment to your craft and your will to get better but on the other hand they might be considered a bit thoughtless, easy and inconsiderate of the work and actual decisions that had to be made by the original designers of the project you are redesigning. These type of projects are a bit dangerous if you only attach your attention to a purely visual exercise instead of a deeper thinking process. I personally still attach a value to these, having done some myself, if only for their technical value and skill practice benefits.
- Self-assigned and original personal projects. For me the best kind of personal projects. Showing not only your technical skills but your analysis, motivations, Interaction skills as well as your ability to be a force of proposition instead of waiting to be told what to do. Especially if you chose to make these projects public, it shows determination and motivation towards your goals. Take the opportunity to learn a technology or technique you didn't know before and it's a home run, showing your will to always keep learning.
In the end it depends on your interviewer and how much they will value industry work versus personal work. It's safe to assume that no matter what you do, personal projects will be valued less than industry project. There are just things like constraints, legacy, budget, team culture and company diplomacy that just cannot be acquired and demonstrated without a business environment experience.
That being said, this shouldn't hold you back from doing as much personal projects as you can because determination will get you where you want to be. If you don't get a company like Google right off the bat, these projects will provide you with the stepping stone you need to get there, via getting you into a better job than you have now where you can build your portfolio.