Welcome! Like others have stated, this is a Windows Phone forum, so naturally people will be biased towards a Windows Phone device.
However, being a former BlackBerry advocate and iPhone user, hopefully my opinion will help you make a decision for yourself.
The Nokia Lumia 1020 is really a special device, simply because of the 41 megapixel shooter on the back - it's incredible
. Plus, the yellow and black model looks really great, at least to me. As for Windows Phone, I switched from iOS 7 last month and I definitely prefer it over iOS, Android and
BlackBerry 10. I'd say the one advantage that BlackBerry 10 has over Windows Phone 8 is an always accessible notification center (i.e. the Hub in BB10.) - but WP8 is built to be 'glance and go.' So it really depends on how you use your device if you really need a dedicated notification center with detailed notes.
As for the getting a BlackBerry Z30 or Lumia 1020, here are some spec comparisons.
The Z30 has a larger screen, at 5'' vs 4.5'' on the 1020, a 2880 mAh battery vs 2000, it's thinner and has HDMI output. However, the Lumia has a higher screen ppi (334 vs 295), a much better camera - the best on the phone market, is lighter and has many more apps available compared to BlackBerry (165000+ vs 120000+.)
If you're a photography aficionado, the Lumia 1020 is definitely more up your alley, otherwise, I'd say it's purely up to what you want in terms of battery life, screen size, camera and more.
In regards to the email and texting experience, here are some screenshots for you to judge:
Messaging Application -
Have fun and feel free to stay around regardless of which phone you choose, it's always fun to have an outsider view on things!