How Many Strollers Can One Have?

When I was adding items onto the baby registry for Brynn I wanted the big gear to work either ways in case we had a boy down the road. The colors worked out for the stroller, car seat, swing, bumbo, high chair, bath tub, exersaucer, etc. But since I have been watching Caitlyn I have come to realize I didn't think the stroller part all the way through. We got the single stroller system but it just doesn't work with 2 kids. I have to hold Brynn and attempt to push the stroller with Caitlyn in the car seat (since she prefers it that way)
Tuesday I saw that Gwen Tautimez had the most amazing stroller that held 2 kids! It works with newborns all the way to at least 5-6! It was a sit and stand stroller. Genius!
I thought to myself why not invest in one especially when I will be using it all the time?! The only thing I am having a problem with is choosing which brand and if I want a single or double? Too many options for someone that thinks way too much about everything! :)

Here is the single sit and stand stroller (this one actually does come with a parent tray)The other single sit and stand stroller (this one has a cool feature-extra carry space for bags)And the double sit and stand stroller (the back seat actually can be taken out to have the same feature as the single but I like the thought of having another seat to recline instead of sitting, but I don't think I will be using it for long days)Thanks for looking and hopefully I can get some advice on which one to invest in. :)