Simcity BuildIt, Transportation or Education perk?

Short version: Go for Transportation and Heliports.

Level 10 is pretty early game, and at your level the biggest benefit to transportation is that you can build the best building (Heliport) immediately after building the Department of Transportation, which is an initial investment of 40,000 Simoleons and 0 golden keys, and then 20 keys for each Heliport.

With education you first have to build the Department of Education, then the Public Library, High School, and Community College before you get access to the University. This mean you have an initial investment of 40,000 Simoleons and 22 golden keys, and then 25 keys for each University. That initial investment of keys takes a significant time to accumulate, about 2 weeks with optimal play.

It's important to note that the Heliport and University provide the same 40% population boost, with different coverages.

As Sorean said, the Heliport is easier to fit into your city and it's cheaper, so I think in most cities the Heliport is the better option to go for first. This is especially true when you only have the low coverage Police and Fire stations (Hospitals later), which consume a lot of your inner-city space and leaves you little room for Universities. Your sims may ask for education, but it doesn't actually affect their happiness.

Of course, later on you can completely cover your city with both transportation and education buildings.

The perk itself doesn't matter all too much since it unlocks buildings that will (as you mention) boost your population. I do find that you can get a bigger boost in comparison to land size taken to build a heliport instead of a university. It's a smaller building that gives the same boost to a smaller area, but easier to put into your infrastructure because it's the same size as a residential house whereas the university is oversized.

It does however unlock different hints, for example if the residential building is by an education building they'll say, "We live by smart sims".