I noticed that the Nexus program has no thread yet, so i will start it.
The Nexus program is a joint USA/Canadian program which allows you GE type entry to USA/Canadian borders and it includes GE membership (and now it includes also TSE Pre) when coming in to the USA.
I have Nexus for the last 2-3 years, and am loving the fact that I it includes Global Entry with it, and + the fee is only $50 vs. $100 for GE.
I signed up my children today on Nexus and I found out that so far there is NO application fee. if it stays this way, this is another reason why I think you should be making Nexus vs. GE.
The only reason not to do it is, that you need to do the interview at a border town or Canadian airport because it's a joint USA/Canadian program.
I flew into YYZ in 2012 or 2013 (can't remember) and completed my application in less than 10 minutes. All in all my cost was 18K Avios, I fly J only :-) but you can it for 9K Avios r/t.