Education wise you need to decide what you are going to do in life. Both programs are different. The advantage of the Lambton college program is that it is a 2 years degree which will give you a 3-year PGWP versus the 1-year PGWP that the Seneca course will give you, but that isn't really going to help unless you know what you are going to do. The Lambton program has a work term which means 4 months of co-op versus the Seneca's 1-month co-op.
Honestly, I don't know much about the career prospects of both courses. To me personally, project management is something that Engineering students take and not B.com students. I would think that courses to do with Marketing or Accounting would be more popular with business students than project management. Also, project management is something that requires experience in another sector.
If I were to put your degree to the program I would personally choose Financial Planning, the course gives you a path towards accreditation which is a requirement for a job. Your degree gives you a background in finance already and hopefully, if you impress the people at the company during your 1 month of co-op you could land a job.
The visa will be the same if you go for either course. Once course at least to me seems more suited to your previous education and the other gives you longer PGWP. Also, do note Seneca facilities in Toronto are more than Lambton college's facilities in Toronto.