Surrey has 20 years to build density around Scott Road, Gateway, Surrey Central and King George. Instead, the fastest growing areas ended up being Newton, South Surrey, and Cloverdale, which are nowhere near the Skytrain stations. Whalley grew by a paltry 10,000 over the last 10 years, which is rather low considering the growth of Surrey as a whole, as the city gained 100,000 during the last decade. There's really no excuse to use the recession considering the comparisons with other suburbs, as under that assumption Richmond/Burnaby/Coquitlam should have suffered greatly from canceled proposals as well. However, we do see that there were still many high-rise projects coming out of these suburbs, all of which have less population increase in both absolute and percentile terms than Surrey.
It's not absolutely necessary for rapid transit to exist to foster high density growth if some planning is in place. For instance, almost 6000 of the 8500 gained in population in Richmond are concentrated within City Centre. Surrey's growth lies in sprawl, not intensification, despite the fact that they already have 4 RRT stations for 18 years. Although there are plans to drastically increase Surrey's city centre density, none of it has materialized yet. If anything, I agree with others' proposal to put one or two B-lines down King George/Fraser to build ridership and pave the way for a future RRT line down these corridors.
In contrast, the Broadway Corridor is an area with significant amount of employment and residential density. There has been many developments in the corridor at the moment, and the 99B is frequently under significant capacity pressure. It simply makes business sense to build RRT there first when money materialize, and arguably it should have been built before Canada Line/Millennium Line/Evergreen Line. It should have greater ridership compared to the other 3 lines as well especially if it is built to connect UBC. As it is, politics/economics have got in the way several times already. As mentioned, people from all over Metro Vancouver (including Surrey) heads to the Broadway corridor, while conversely there are markedly fewer people heading to Surrey Central. The Broadway corridor draws many people from all over the North Shore, Vancouver, Richmond, Burnaby, and increasingly the Tri-Cities. A Surrey line will almost solely be utilized by people in Surrey and Langley/White Rock. A Broadway Line, once built, will save Translink money by cutting down on operating cost and most likely generate a small profit from the line itself, due to the high density of the area along with the cutting of numerous bus routes which obviously have a high operating cost. This will generate momentum in getting new transit lines, as a successful RRT line will increase both economical and political support for translink. While I also believe that a Surrey line will certainly be well utilized, I doubt it will generate nearly as much ridership as the Broadway line, and thus the opportunity for detractors to label RRT as a useless boondoggle again.
That is not accounting for the significant road/bridge work that is taking place SoF, which will clearly benefit people SoF more even if it is benefiting the region as a whole. A SoF commuter can not only benefit from improved logistics of the economy, but also actively use new roadways and bridges frequently. Someone in say North Vancouver may benefit from said improved economics, but rarely will they be able to use the Golden Ears bridge because there's no reason to.
Of course, it would be great if both lines can be funded at the same time, but that's not going to happen. However, I believe a Broadway line is more beneficial to the whole metro and makes more sense to build first.