For me its this.

Empower:

Pros:
1. Fast - I don't have to wait for html to render when i open an email.
2. Very lightweight - 27kb or something.
3. Tighter integration with native email - I can delete from "mailbox and handheld" as well as handheld. So i can reconcile deleted items later. Also most of my native functions work.
4. foreign language packs work fine.

cons -
1. still in beta development.

Smartview:
Pros
1. supports background colors. more options for settings.

cons
1. Slow - i had to wait for sometime before the html showed, at times upto 5 seconds.
2. Some of the functions didn't work for me.
3. Okay, this last one is not related to me, but just so that i mention - it is not able to display correctly on devices with foreign fonts installed.


As you can see, I didn't include price (SV charging $25, Empower free) in my comparsion. Have compared the features, price is an individual issue so that is not a feature comparision..

Overall, i think empower is pointed in the right direction - they talk about folders, and spellcheck and other things.. so i think they have a longterm view..