The only downside to Spitfire it that you have to look in two places, and kontakt involves one extra step (that you have to do for any kontakt package). The latest Spitfire stuff, the way my system is set up, has them in the right hand side panel, and kontakt is in that list too, so some Spitfire items are there, others are inside kontakt. In practice, it's just mildy annoying remembering where a certain thing is. I've just got British Drama Toolkit, the brass and reed version, the original I've had for ages and really like the way it works. I'm having great fun with it. I missed it when it first came out. Spitfire emailed a special offer code, so found it there, then discovered the price for me, when I logged in was cheaper than the special offer price.
On a totally separate topic - Spitfire have some excellent videos, especially the series where they are building their London Studios in an empty building. Some useful studio building tips there.